Screw Thread and Tap Drill API

API ID 14694

Thread sizes, tap drills, clearance holes and drill bits for metric, UNC/UNF and NPT pipe threads.

API Documentation

Endpoints

Request
A designation like M6, M6x1, M8x1, 1/4-20, 1/4-20 UNC, #10-32 or 1-1/4-7 (URL-encode the slash: 1%2F4-20, or use GET /thread?designation=). basicProfile: major, pitch and minor diameters (internal and external) and thread depths in mm and inches, computed from the basic profile. tapDrill: the ideal hole for the percent of thread, the nearest standard bit in the thread's own system and in the other one, with the percent of thread each gives. clearanceHole: close, normal and loose. hex: wrench (across flats) and hex key sizes. standard: false for a size or pitch outside the standard series (still computed).
Endpoint ID: 37985
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37985/everything+about+one+thread
INPUT PARAMETERS

Everything about one thread — Endpoint Features

Object Description
percent Optional Percent of thread for the tap drill, 50-90 (default 75).
designation Required

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

percent
API EXAMPLE RESPONSE
JSON
{
    "thread": {
        "designation": "M6x1",
        "system": "metric",
        "series": "coarse",
        "size": "M6",
        "nominalDiameter": {
            "mm": 6,
            "in": 0.2362
        },
        "pitch": {
            "mm": 1,
            "in": 0.0394
        },
        "threadsPerInch": 25.4,
        "standard": true,
        "alsoWritten": "M6",
        "basicProfile": {
            "majorDiameter": {
                "mm": 6,
                "in": 0.2362
            },
            "pitchDiameter": {
                "mm": 5.35,
                "in": 0.2106
            },
            "minorDiameterInternal": {
                "mm": 4.917,
                "in": 0.1936
            },
            "minorDiameterExternal": {
                "mm": 4.773,
                "in": 0.1879
            },
            "threadDepthInternal": {
                "mm": 0.541,
                "in": 0.0213
            },
            "threadDepthExternal": {
                "mm": 0.613,
                "in": 0.0242
            },
            "fundamentalTriangleHeight": {
                "mm": 0.866,
                "in": 0.0341
            }
        },
        "tapDrill": {
            "percentRequested": 75,
            "idealDiameter": {
                "mm": 5.026,
                "in": 0.1979
            },
            "recommended": {
                "name": "5.0 mm",
                "family": "metric",
                "mm": 5,
                "in": 0.1969,
                "percentThread": 77
            },
            "otherSystem": {
                "name": "#8",
                "family": "number",
                "mm": 5.055,
                "in": 0.199,
                "percentThread": 72.7
            },
            "basicMinorDiameterInternal": {
                "mm": 4.917,
                "in": 0.1936
            },
            "note": "Percent of thread = (major diameter − drill) ÷ (1.299 × pitch). 65-75% suits most work; 50-60% for hard or tough materials and deep holes; up to 80% in soft materials and thin sheet. Thread-forming (roll) taps need a larger hole."
        },
        "clearanceHole": {
            "available": true,
            "basis": "iso273",
            "close": {
                "mm": 6.4,
                "in": 0.252,
                "inchBit": {
                    "name": "F",
                    "family": "letter",
                    "mm": 6.528,
                    "in": 0.257
                }
            },
            "normal": {
                "mm": 6.6,
                "in": 0.2598,
                "inchBit": {
                    "name": "G",
                    "family": "letter",
                    "mm": 6.629,
                    "in": 0.261
                }
            },
            "loose": {
                "mm": 7,
                "in": 0.2756,
                "inchBit": {
                    "name": "J",
                    "family": "letter",
                    "mm": 7.036,
                    "in": 0.277
                }
            },
            "note": "close, normal and loose are the standard's fine, medium and coarse series. inchBit is the smallest inch bit at or above the hole, if you only have inch drills."
        },
        "hex": {
            "wrench": {
                "mm": 10,
                "in": 0.3937
            },
            "hexKey": {
                "mm": 5
            }
        },
        "sameSize": [
            "M6x0.75"
        ]
    },
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
Everything about one thread — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37985/everything+about+one+thread&designation=Required' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
Same answer as /thread/{designation}; handy for inch sizes with a slash (designation=1/4-20).
Endpoint ID: 37986
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37986/the+same+with+the+designation+as+a+query+parameter
INPUT PARAMETERS

The same with the designation as a query parameter — Endpoint Features

Object Description
designation Required Thread designation.
percent Optional Percent of thread (50-90, default 75).

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

designation
percent
API EXAMPLE RESPONSE
JSON
{
    "thread": {
        "designation": "1/4-20 UNC",
        "system": "inch",
        "series": "UNC",
        "size": "1/4",
        "nominalDiameter": {
            "mm": 6.35,
            "in": 0.25
        },
        "pitch": {
            "mm": 1.27,
            "in": 0.05
        },
        "threadsPerInch": 20,
        "standard": true,
        "basicProfile": {
            "majorDiameter": {
                "mm": 6.35,
                "in": 0.25
            },
            "pitchDiameter": {
                "mm": 5.525,
                "in": 0.2175
            },
            "minorDiameterInternal": {
                "mm": 4.975,
                "in": 0.1959
            },
            "minorDiameterExternal": {
                "mm": 4.838,
                "in": 0.1905
            },
            "threadDepthInternal": {
                "mm": 0.687,
                "in": 0.0271
            },
            "threadDepthExternal": {
                "mm": 0.756,
                "in": 0.0298
            },
            "fundamentalTriangleHeight": {
                "mm": 1.1,
                "in": 0.0433
            }
        },
        "tapDrill": {
            "percentRequested": 75,
            "idealDiameter": {
                "mm": 5.113,
                "in": 0.2013
            },
            "recommended": {
                "name": "#7",
                "family": "number",
                "mm": 5.105,
                "in": 0.201,
                "percentThread": 75.5
            },
            "otherSystem": {
                "name": "5.1 mm",
                "family": "metric",
                "mm": 5.1,
                "in": 0.2008,
                "percentThread": 75.8
            },
            "basicMinorDiameterInternal": {
                "mm": 4.975,
                "in": 0.1959
            },
            "note": "Percent of thread = (major diameter − drill) ÷ (1.299 × pitch). 65-75% suits most work; 50-60% for hard or tough materials and deep holes; up to 80% in soft materials and thin sheet. Thread-forming (roll) taps need a larger hole."
        },
        "clearanceHole": {
            "available": true,
            "basis": "rule",
            "close": {
                "mm": 6.528,
                "in": 0.257,
                "bit": {
                    "name": "F",
                    "family": "letter",
                    "mm": 6.528,
                    "in": 0.257
                },
                "metricBit": {
                    "name": "6.5 mm",
                    "family": "metric",
                    "mm": 6.5,
                    "in": 0.2559
                }
            },
            "normal": {
                "mm": 6.747,
                "in": 0.2656,
                "bit": {
                    "name": "17/64\"",
                    "family": "fractional",
                    "mm": 6.747,
                    "in": 0.265625
                },
                "metricBit": {
                    "name": "6.8 mm",
                    "family": "metric",
                    "mm": 6.8,
                    "in": 0.2677
                }
            },
            "loose": {
                "mm": 7.137,
                "in": 0.281,
                "bit": {
                    "name": "K",
                    "family": "letter",
                    "mm": 7.137,
                    "in": 0.281
                },
                "metricBit": {
                    "name": "7.2 mm",
                    "family": "metric",
                    "mm": 7.2,
                    "in": 0.2835
                }
            },
            "note": "Common US shop practice: the smallest standard bit at or above d + 2% (close, at least 0.004 in), d + 6% (normal, at least 0.010 in) or d + 12% (loose, at least 0.020 in). Shops and tables differ by a bit size either way."
        },
        "hex": {
            "wrench": {
                "fraction": "7/16",
                "in": 0.4375,
                "mm": 11.112
            },
            "hexKey": {
                "fraction": "3/16",
                "in": 0.1875,
                "mm": 4.762
            }
        },
        "sameSize": [
            "1/4-28 UNF",
            "1/4-32 UNEF"
        ]
    },
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
The same with the designation as a query parameter — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37986/the+same+with+the+designation+as+a+query+parameter?designation=1/4-20' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
recommended: the nearest standard bit to the ideal hole in the thread's own system (metric bits for metric threads; fractional, number and letter for inch), otherSystem: the nearest in the other system, choices: every bit in the own system that gives 50-90% thread, largest first, each with its percent. Percent of thread = (major − drill) ÷ (1.299 × pitch).
Endpoint ID: 37987
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37987/tap+drill+for+a+thread+and+percent+of+thread
INPUT PARAMETERS

Tap drill for a thread and percent of thread — Endpoint Features

Object Description
thread Required Thread designation.
percent Optional Percent of thread (50-90, default 75).

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

thread
percent
API EXAMPLE RESPONSE
JSON
{
    "thread": {
        "designation": "M8x1.25",
        "system": "metric",
        "series": "coarse",
        "size": "M8",
        "nominalDiameter": {
            "mm": 8,
            "in": 0.315
        },
        "pitch": {
            "mm": 1.25,
            "in": 0.0492
        },
        "threadsPerInch": 20.32,
        "standard": true
    },
    "tapDrill": {
        "percentRequested": 75,
        "idealDiameter": {
            "mm": 6.782,
            "in": 0.267
        },
        "recommended": {
            "name": "6.8 mm",
            "family": "metric",
            "mm": 6.8,
            "in": 0.2677,
            "percentThread": 73.9
        },
        "otherSystem": {
            "name": "H",
            "family": "letter",
            "mm": 6.756,
            "in": 0.266,
            "percentThread": 76.6
        },
        "choices": [
            {
                "name": "7.1 mm",
                "family": "metric",
                "mm": 7.1,
                "in": 0.2795,
                "percentThread": 55.4
            },
            {
                "name": "7.0 mm",
                "family": "metric",
                "mm": 7,
                "in": 0.2756,
                "percentThread": 61.6
            },
            {
                "name": "6.9 mm",
                "family": "metric",
                "mm": 6.9,
                "in": 0.2717,
                "percentThread": 67.7
            },
            {
                "name": "6.8 mm",
                "family": "metric",
                "mm": 6.8,
                "in": 0.2677,
                "percentThread": 73.9
            },
            {
                "name": "6.7 mm",
                "family": "metric",
                "mm": 6.7,
                "in": 0.2638,
                "percentThread": 80.1
            },
            {
                "name": "6.6 mm",
                "family": "metric",
                "mm": 6.6,
                "in": 0.2598,
                "percentThread": 86.2
            }
        ],
        "basicMinorDiameterInternal": {
            "mm": 6.647,
            "in": 0.2617
        },
        "note": "Percent of thread = (major diameter − drill) ÷ (1.299 × pitch). 65-75% suits most work; 50-60% for hard or tough materials and deep holes; up to 80% in soft materials and thin sheet. Thread-forming (roll) taps need a larger hole."
    },
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
Tap drill for a thread and percent of thread — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37987/tap+drill+for+a+thread+and+percent+of+thread?thread=M8&percent=75' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
Metric: the standard close, normal and loose clearance holes, with the smallest inch bit that clears. Inch: the smallest standard bit at or above d + 2% (close), 6% (normal) or 12% (loose), with minimum allowances, and the smallest metric bit that clears. fit picks one.
Endpoint ID: 37988
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37988/clearance+holes+close+normal+loose+and+hex+sizes
INPUT PARAMETERS

Clearance holes close normal loose and hex sizes — Endpoint Features

Object Description
thread Required Thread designation (or just the size: M10, 3/8).
fit Optional close, normal or loose (default: all three).

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

thread
fit
API EXAMPLE RESPONSE
JSON
{
    "thread": {
        "designation": "M10x1.5",
        "system": "metric",
        "series": "coarse",
        "size": "M10",
        "nominalDiameter": {
            "mm": 10,
            "in": 0.3937
        },
        "pitch": {
            "mm": 1.5,
            "in": 0.0591
        },
        "threadsPerInch": 16.933,
        "standard": true
    },
    "clearanceHole": {
        "fit": "close",
        "hole": {
            "mm": 10.5,
            "in": 0.4134,
            "inchBit": {
                "name": "27/64\"",
                "family": "fractional",
                "mm": 10.716,
                "in": 0.421875
            }
        },
        "note": "close, normal and loose are the standard's fine, medium and coarse series. inchBit is the smallest inch bit at or above the hole, if you only have inch drills."
    },
    "hex": {
        "wrench": {
            "mm": 16,
            "in": 0.6299
        },
        "hexKey": {
            "mm": 8
        },
        "dinWrench": {
            "mm": 17
        },
        "note": "Older DIN 931/933/934 parts use a 17 mm wrench."
    },
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
Clearance holes close normal loose and hex sizes — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37988/clearance+holes+close+normal+loose+and+hex+sizes?thread=M10&fit=close' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
size: 5.1mm, 0.201in, 13/64, or a number with unit=mm or unit=in. system: all (default), inch (fractional, number, letter), metric, fractional, number, letter, or a comma list. nearest (with the difference), nextSmaller, nextLarger, and with more than one family the nearest in each (bySystem).
Endpoint ID: 37989
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37989/nearest+standard+drill+bit+to+a+size
INPUT PARAMETERS

Nearest standard drill bit to a size — Endpoint Features

Object Description
size Required A length. (size parameter)
unit Optional mm or in, for a bare number.
system Optional Which bits.

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

size
unit
system
API EXAMPLE RESPONSE
JSON
{
    "size": {
        "mm": 5.1,
        "in": 0.2008
    },
    "system": [
        "fractional",
        "number",
        "letter",
        "metric"
    ],
    "nearest": {
        "name": "5.1 mm",
        "family": "metric",
        "mm": 5.1,
        "in": 0.2008,
        "differenceMm": 0,
        "differenceIn": 0
    },
    "nextSmaller": {
        "name": "#8",
        "family": "number",
        "mm": 5.055,
        "in": 0.199
    },
    "nextLarger": {
        "name": "#7",
        "family": "number",
        "mm": 5.105,
        "in": 0.201
    },
    "bySystem": {
        "fractional": {
            "name": "13/64\"",
            "family": "fractional",
            "mm": 5.159,
            "in": 0.203125,
            "differenceMm": 0.059,
            "differenceIn": 0.0023
        },
        "number": {
            "name": "#7",
            "family": "number",
            "mm": 5.105,
            "in": 0.201,
            "differenceMm": 0.005,
            "differenceIn": 0.0002
        },
        "letter": {
            "name": "A",
            "family": "letter",
            "mm": 5.944,
            "in": 0.234,
            "differenceMm": 0.844,
            "differenceIn": 0.0332
        },
        "metric": {
            "name": "5.1 mm",
            "family": "metric",
            "mm": 5.1,
            "in": 0.2008,
            "differenceMm": 0,
            "differenceIn": 0
        }
    },
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
Nearest standard drill bit to a size — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37989/nearest+standard+drill+bit+to+a+size?size=5.1mm&unit=mm&system=all' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
Number (#7, URL-encoded %237), letter (F), fraction (7/32, encoded 7%2F32) or metric (5.5mm). tapDrillFor lists the standard threads whose 75% tap drill is this bit. Not in the index: found: false.
Endpoint ID: 37990
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37990/a+drill+bit+by+name+size+nearest+in+the+other+system+threads+it+taps
INPUT PARAMETERS

Free test requests remaining: 3 of 3.

API EXAMPLE RESPONSE
JSON
{
    "found": true,
    "drill": {
        "name": "#7",
        "family": "number",
        "mm": 5.105,
        "in": 0.201
    },
    "nearestInOtherSystem": {
        "name": "5.1 mm",
        "family": "metric",
        "mm": 5.1,
        "in": 0.2008,
        "differenceMm": -0.005,
        "differenceIn": -0.0002
    },
    "tapDrillFor": [
        "1/4-20 UNC"
    ],
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
A drill bit by name size nearest in the other system threads it taps — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37990/a+drill+bit+by+name+size+nearest+in+the+other+system+threads+it+taps&name=Required' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
q: M6, M10, 1/4, #10, 10-32 (the exact thread first, then the same size). diameter: 6.2mm or 0.25in (or a number with unit) finds threads in both systems within 6%, nearest first. Filters: system, series.
Endpoint ID: 37991
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37991/find+threads+by+designation+text+or+by+diameter
INPUT PARAMETERS

Find threads by designation text or by diameter — Endpoint Features

Object Description
q Optional Designation or size.
diameter Optional A diameter.
unit Optional mm or in for a bare number.
system Optional metric or inch.
series Optional coarse, fine, unc, unf or unef.
limit Optional 1-100 (default 20).

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

q
diameter
unit
system
series
limit
API EXAMPLE RESPONSE
JSON
{
    "q": "1/4",
    "diameter": {
        "mm": 6.2,
        "in": 0.2441
    },
    "count": 0,
    "total": 0,
    "threads": [],
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
Find threads by designation text or by diameter — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37991/find+threads+by+designation+text+or+by+diameter?q=1/4&diameter=6.2mm&unit=mm&system=metric&series=coarse' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
Every standard thread (compact), with filters
Endpoint ID: 37992
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37992/every+standard+thread+compact+with+filters
INPUT PARAMETERS

Every standard thread compact with filters — Endpoint Features

Object Description
system Optional metric or inch.
series Optional coarse, fine, unc, unf or unef.

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

system
series
API EXAMPLE RESPONSE
JSON
{
    "count": 0,
    "threads": [],
    "disclaimer": "Reference values computed from the basic thread profiles and common shop practice; not for safety-critical design. Tolerance classes, materials and tap makers' recommendations change the right hole size: check the standard, the fastener maker's data and a test piece before production."
}
Every standard thread compact with filters — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37992/every+standard+thread+compact+with+filters?system=metric&series=unc' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
A nominal pipe size from 1/16 to 2 in: 1/2, 1/2-14, 1/2-14 NPT, 3/4 NPT, 1-1/4 or 1-1/4-11.5 (URL-encode the slash: 1%2F2, or use GET /npt?size=). Every value is computed from the taper pipe thread formulas (taper 1 in 16 on the diameter; pitch diameter at the pipe end E0 = D − (0.05D + 1.1)p; at the hand-tight plane E1 = E0 + L1/16; effective thread L2 = (0.80D + 6.8)p; thread height 0.8p): pitchDiameter (E0, E1, E2, E5, E3), major and minor diameters at the pipe end and the hand-tight plane, lengths (hand-tight engagement, effective thread, wrench makeup, vanish, overall, perfect threads, minimum internal thread) in inches, mm and threads. tapDrillPracticeGuide: not a value of the standard; two common rules (largest bit not above the minor diameter at the hand-tight plane, or at the small end after wrench makeup), each with an inch and a metric bit. A wrong threads-per-inch is refused. Not for gas, pressure or safety-critical work.
Endpoint ID: 37998
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37998/npt+taper+pipe+thread+computed+dimensions+and+a+tap-drill+guide
INPUT PARAMETERS

Free test requests remaining: 3 of 3.

API EXAMPLE RESPONSE
JSON
{
    "pipeThread": {
        "designation": "1/2-14 NPT",
        "nominalSize": "1/2",
        "threadsPerInch": 14,
        "outsideDiameterOfPipe": {
            "in": 0.84,
            "mm": 21.336
        },
        "pitch": {
            "in": 0.07143,
            "mm": 1.814
        },
        "taper": {
            "onDiameter": "1 in 16",
            "inchesPerFoot": 0.75,
            "halfAngleDegrees": 1.7899,
            "halfAngle": "1° 47' 24\"",
            "diameterIncreasePerThread": {
                "in": 0.00446,
                "mm": 0.113
            }
        },
        "threadForm": {
            "flankAngleDegrees": 60,
            "sharpVHeight": {
                "in": 0.06186,
                "mm": 1.571
            },
            "threadHeight": {
                "in": 0.05714,
                "mm": 1.451
            },
            "truncation": "flat crests and roots; basic thread height 0.8 × pitch"
        },
        "pitchDiameter": {
            "atPipeEnd": {
                "symbol": "E0",
                "in": 0.75843,
                "mm": 19.264
            },
            "atHandTightPlane": {
                "symbol": "E1",
                "in": 0.77843,
                "mm": 19.772
            },
            "atEndOfEffectiveThread": {
                "symbol": "E2",
                "in": 0.79179,
                "mm": 20.111
            },
            "atEndOfPerfectThread": {
                "symbol": "E5",
                "in": 0.78286,
                "mm": 19.885
            },
            "atInternalSmallEnd": {
                "symbol": "E3",
                "in": 0.74504,
                "mm": 18.924
            }
        },
        "atPipeEnd": {
            "majorDiameter": {
                "in": 0.81557,
                "mm": 20.716
            },
            "minorDiameter": {
                "in": 0.70129,
                "mm": 17.813
            }
        },
        "atHandTightPlane": {
            "majorDiameter": {
                "in": 0.83557,
                "mm": 21.224
            },
            "minorDiameter": {
                "in": 0.72129,
                "mm": 18.321
            }
        },
        "lengths": {
            "handTightEngagement": {
                "symbol": "L1",
                "in": 0.32,
                "mm": 8.128,
                "threads": 4.48
            },
            "effectiveExternalThread": {
                "symbol": "L2",
                "in": 0.5337,
                "mm": 13.556,
                "threads": 7.47
            },
            "wrenchMakeup": {
                "symbol": "L3",
                "in": 0.2143,
                "mm": 5.443,
                "threads": 3
            },
            "vanishThreads": {
                "symbol": "V",
                "in": 0.2479,
                "mm": 6.296,
                "threads": 3.47
            },
            "overallExternalThread": {
                "symbol": "L4",
                "in": 0.7816,
                "mm": 19.852,
                "threads": 10.94
            },
            "perfectExternalThreads": {
                "symbol": "L5",
                "in": 0.3909,
                "mm": 9.928,
                "threads": 5.47
            },
            "minimumInternalThread": {
                "symbol": "L1+L3",
                "in": 0.5343,
                "mm": 13.571,
                "threads": 7.48
            }
        },
        "tapDrillPracticeGuide": {
            "standardValue": false,
            "note": "A common-practice guide, not a dimension of the pipe-thread standard: charts disagree by about one drill size, so both usual rules are given. Each bit is the largest standard bit not above the internal thread's basic minor diameter at that plane.",
            "handTightPlane": {
                "basis": "minor diameter at the hand-tight (gauge) plane: E1 − h",
                "minorDiameter": {
                    "in": 0.72129,
                    "mm": 18.321
                },
                "inchBit": {
                    "name": "23/32\"",
                    "family": "fractional",
                    "in": 0.71875,
                    "mm": 18.256
                },
                "metricBit": {
                    "name": "18.0 mm",
                    "family": "metric",
                    "in": 0.7087,
                    "mm": 18
                },
                "use": "The size most charts print; tap straight from the drilled hole."
            },
            "smallEnd": {
                "basis": "minor diameter at the small end of the internal thread after wrench makeup (L1 + L3 deep): E3 − h",
                "minorDiameter": {
                    "in": 0.68789,
                    "mm": 17.472
                },
                "inchBit": {
                    "name": "11/16\"",
                    "family": "fractional",
                    "in": 0.6875,
                    "mm": 17.463
                },
                "metricBit": {
                    "name": "17.0 mm",
                    "family": "metric",
                    "in": 0.6693,
                    "mm": 17
                },
                "use": "One size smaller: full thread to the bottom of the engagement; the usual start before a taper pipe reamer."
            },
            "reamFirst": "For tight joints in hard or thick material, drill the smaller size, ream with a 3/4 in per foot taper pipe reamer, then tap. Tap until a plug gauge sits at the hand-tight plane within one turn."
        },
        "note": "Basic dimensions. The product tolerance is one turn of the gauge large or small from basic. L1 (hand-tight engagement) is the standard's gauge length; every other value is computed from the formulas."
    },
    "disclaimer": "Reference values only: basic dimensions computed from the taper pipe thread formulas; not for gas, pressure or other safety-critical work. The tap drill is a common-practice guide, not a value of the standard. Check the current pipe thread standard, the fitting maker's data and a thread gauge before use."
}
NPT taper pipe thread computed dimensions and a tap-drill guide — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37998/npt+taper+pipe+thread+computed+dimensions+and+a+tap-drill+guide&size=Required' --header 'Authorization: Bearer YOUR_API_KEY' 


    
Request
With size (e.g. size=3/4-14 NPT): the same answer as /npt/{size}. Without: the ten covered sizes (designation, threads per inch, pipe outside diameter); ask /npt/{size} for the computed values.
Endpoint ID: 37999
GET https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37999/npt+by+query+parameter+or+the+list+of+covered+sizes
INPUT PARAMETERS

NPT by query parameter or the list of covered sizes — Endpoint Features

Object Description
size Optional Nominal pipe size, 1/16 to 2 (optional).

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

size
API EXAMPLE RESPONSE
JSON
{
    "pipeThread": {
        "designation": "3/4-14 NPT",
        "nominalSize": "3/4",
        "threadsPerInch": 14,
        "outsideDiameterOfPipe": {
            "in": 1.05,
            "mm": 26.67
        },
        "pitch": {
            "in": 0.07143,
            "mm": 1.814
        },
        "taper": {
            "onDiameter": "1 in 16",
            "inchesPerFoot": 0.75,
            "halfAngleDegrees": 1.7899,
            "halfAngle": "1° 47' 24\"",
            "diameterIncreasePerThread": {
                "in": 0.00446,
                "mm": 0.113
            }
        },
        "threadForm": {
            "flankAngleDegrees": 60,
            "sharpVHeight": {
                "in": 0.06186,
                "mm": 1.571
            },
            "threadHeight": {
                "in": 0.05714,
                "mm": 1.451
            },
            "truncation": "flat crests and roots; basic thread height 0.8 × pitch"
        },
        "pitchDiameter": {
            "atPipeEnd": {
                "symbol": "E0",
                "in": 0.96768,
                "mm": 24.579
            },
            "atHandTightPlane": {
                "symbol": "E1",
                "in": 0.98887,
                "mm": 25.117
            },
            "atEndOfEffectiveThread": {
                "symbol": "E2",
                "in": 1.00179,
                "mm": 25.445
            },
            "atEndOfPerfectThread": {
                "symbol": "E5",
                "in": 0.99286,
                "mm": 25.219
            },
            "atInternalSmallEnd": {
                "symbol": "E3",
                "in": 0.95429,
                "mm": 24.239
            }
        },
        "atPipeEnd": {
            "majorDiameter": {
                "in": 1.02482,
                "mm": 26.03
            },
            "minorDiameter": {
                "in": 0.91054,
                "mm": 23.128
            }
        },
        "atHandTightPlane": {
            "majorDiameter": {
                "in": 1.04601,
                "mm": 26.569
            },
            "minorDiameter": {
                "in": 0.93172,
                "mm": 23.666
            }
        },
        "lengths": {
            "handTightEngagement": {
                "symbol": "L1",
                "in": 0.339,
                "mm": 8.611,
                "threads": 4.75
            },
            "effectiveExternalThread": {
                "symbol": "L2",
                "in": 0.5457,
                "mm": 13.861,
                "threads": 7.64
            },
            "wrenchMakeup": {
                "symbol": "L3",
                "in": 0.2143,
                "mm": 5.443,
                "threads": 3
            },
            "vanishThreads": {
                "symbol": "V",
                "in": 0.2479,
                "mm": 6.296,
                "threads": 3.47
            },
            "overallExternalThread": {
                "symbol": "L4",
                "in": 0.7936,
                "mm": 20.157,
                "threads": 11.11
            },
            "perfectExternalThreads": {
                "symbol": "L5",
                "in": 0.4029,
                "mm": 10.233,
                "threads": 5.64
            },
            "minimumInternalThread": {
                "symbol": "L1+L3",
                "in": 0.5533,
                "mm": 14.053,
                "threads": 7.75
            }
        },
        "tapDrillPracticeGuide": {
            "standardValue": false,
            "note": "A common-practice guide, not a dimension of the pipe-thread standard: charts disagree by about one drill size, so both usual rules are given. Each bit is the largest standard bit not above the internal thread's basic minor diameter at that plane.",
            "handTightPlane": {
                "basis": "minor diameter at the hand-tight (gauge) plane: E1 − h",
                "minorDiameter": {
                    "in": 0.93172,
                    "mm": 23.666
                },
                "inchBit": {
                    "name": "59/64\"",
                    "family": "fractional",
                    "in": 0.921875,
                    "mm": 23.416
                },
                "metricBit": {
                    "name": "23.5 mm",
                    "family": "metric",
                    "in": 0.9252,
                    "mm": 23.5
                },
                "use": "The size most charts print; tap straight from the drilled hole."
            },
            "smallEnd": {
                "basis": "minor diameter at the small end of the internal thread after wrench makeup (L1 + L3 deep): E3 − h",
                "minorDiameter": {
                    "in": 0.89714,
                    "mm": 22.787
                },
                "inchBit": {
                    "name": "57/64\"",
                    "family": "fractional",
                    "in": 0.890625,
                    "mm": 22.622
                },
                "metricBit": {
                    "name": "22.5 mm",
                    "family": "metric",
                    "in": 0.8858,
                    "mm": 22.5
                },
                "use": "One size smaller: full thread to the bottom of the engagement; the usual start before a taper pipe reamer."
            },
            "reamFirst": "For tight joints in hard or thick material, drill the smaller size, ream with a 3/4 in per foot taper pipe reamer, then tap. Tap until a plug gauge sits at the hand-tight plane within one turn."
        },
        "note": "Basic dimensions. The product tolerance is one turn of the gauge large or small from basic. L1 (hand-tight engagement) is the standard's gauge length; every other value is computed from the formulas."
    },
    "disclaimer": "Reference values only: basic dimensions computed from the taper pipe thread formulas; not for gas, pressure or other safety-critical work. The tap drill is a common-practice guide, not a value of the standard. Check the current pipe thread standard, the fitting maker's data and a thread gauge before use."
}
NPT by query parameter or the list of covered sizes — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/14694/screw+thread+and+tap+drill+api/37999/npt+by+query+parameter+or+the+list+of+covered+sizes?size=3/4-14 NPT' --header 'Authorization: Bearer YOUR_API_KEY' 


    

API Access Key & Authentication

After signing up, every developer is assigned a personal API access key, a unique combination of letters and digits provided to access to our API endpoint. To authenticate with the Screw Thread and Tap Drill API simply include your bearer token in the Authorization header.

Headers
Header Description
Authorization Required Should be Bearer access_key. See "Your API Access Key" above when you are subscribed.

No long-term commitment. Upgrade, downgrade, or cancel anytime.

Starts at
$10,000/Year


  • Custom Volume
  • Custom Rate Limit
  • Specialized Customer Support
  • Real-Time API Monitoring

Overview

Thread sizes, tap drills, clearance holes and drill bits for metric, UNC/UNF and NPT pipe threads.

Screw Thread and Tap Drill API FAQs

The standard bit nearest the ideal hole for your percent of thread (default 75%), in the thread's own system, plus the nearest in the other system. Each comes with the percent of thread it really gives, and /tapdrill lists every bit from 50% to 90% so you can choose.

No. Major, pitch and minor diameters are computed from the basic thread profile formulas for every request, so non-standard pitches (M6x0.5) work too and are marked standard: false.

Not yet: the dimensions are basic sizes. A class written in the designation is accepted and ignored.

The smallest standard bit at or above the screw diameter plus 2% (close), 6% (normal) or 12% (loose), with small minimums. Metric holes follow the standard close, normal and loose series.

No. Each call is computed in memory and nothing is logged.

Yes, NPT taper pipe threads from 1/16 to 2 in (GET /npt/{size}): pitch diameters, lengths and thread height computed from the taper pipe thread formulas. Dryseal NPTF, straight NPS and British BSP threads are not covered. Not for gas, pressure or other safety-critical work.

Pipe tap drills are shop practice, not part of the standard, and charts differ by one size. The API gives the largest bit under the minor diameter at the hand-tight plane (the size most charts print, 23/32 for 1/2 NPT) and at the small end of the thread (one size smaller, 11/16, the start before a taper reamer).

Each endpoint returns detailed information about thread sizes, tap drills, clearance holes, and drill bits. For example, the GET /thread endpoint provides major, pitch, and minor diameters, while the GET /tapdrill endpoint offers recommended drill sizes based on thread specifications.

Key fields include "designation," "system," "nominalDiameter," "pitch," and "standard." For tap drill responses, fields like "recommended," "idealDiameter," and "percentThread" are crucial for understanding drill size recommendations.

Parameters vary by endpoint. For example, GET /thread accepts "designation" to specify the thread type, while GET /tapdrill requires "percentRequested" to define the desired thread engagement percentage. Users can also filter by "system" and "series."

Response data is structured in JSON format, with nested objects for clarity. For instance, the "thread" object contains details like "nominalDiameter" and "pitch," while the "tapDrill" object includes "recommended" drill sizes and their specifications.

Each endpoint provides specific information: GET /thread offers thread dimensions, GET /tapdrill gives drill size recommendations, and GET /clearance provides clearance hole sizes. NPT endpoints detail pipe thread dimensions and tap-drill guides.

Users can customize requests by specifying parameters such as "designation" for threads, "percentRequested" for tap drills, or "size" for NPT threads. This allows for tailored responses based on specific needs or criteria.

Typical use cases include selecting appropriate drill sizes for threading applications, determining clearance hole dimensions for fasteners, and referencing pipe thread specifications for plumbing projects. Engineers and machinists frequently utilize this data.

Data accuracy is maintained through computation based on established thread profile formulas. Each request generates real-time calculations, ensuring that dimensions reflect current standards and practices, rather than relying on static charts.

General FAQs

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