Thread standards are the bread and butter of most design projects. If you are designing aftermarket parts or reverse engineering components identifying threads is a common task to ensure part compatibility. So to help things along we have drafted up a list of common threads you are likely to encounter, their dimensions together with tapping and clearance drill sizes.
ISO Metric Thread Standards – Coarse and Fine
Common Uses: ISO Metric threads are the most widely adopted thread system globally, used in machinery, automotive, and construction industries.
Year Introduced: 1947
Thread Angle: 60°
Regions: Worldwide, especially in countries using the metric system.
ISO Metric Coarse Threads:
| Thread (M) | Pitch (mm) | Major Dia (mm) | Minor Dia (mm) | Tap Drill (mm) | Clearance Hole (mm) |
|---|---|---|---|---|---|
| M1.6 | 0.35 | 1.60 | 1.25 | 1.25 | 1.8 |
| M2 | 0.40 | 2.00 | 1.60 | 1.60 | 2.2 |
| M2.5 | 0.45 | 2.50 | 2.05 | 2.05 | 2.7 |
| M3 | 0.50 | 3.00 | 2.50 | 2.50 | 3.4 |
| M3.5 | 0.60 | 3.50 | 2.90 | 2.90 | 3.9 |
| M4 | 0.70 | 4.00 | 3.30 | 3.30 | 4.5 |
| M5 | 0.80 | 5.00 | 4.20 | 4.20 | 5.5 |
| M6 | 1.00 | 6.00 | 5.00 | 5.00 | 6.6 |
| M7 | 1.00 | 7.00 | 6.00 | 6.00 | 7.6 |
| M8 | 1.25 | 8.00 | 6.75 | 6.80 | 8.8 |
| M10 | 1.50 | 10.00 | 8.50 | 8.50 | 11.0 |
| M12 | 1.75 | 12.00 | 10.20 | 10.20 | 13.5 |
| M14 | 2.00 | 14.00 | 12.00 | 12.00 | 15.5 |
| M16 | 2.00 | 16.00 | 14.00 | 14.00 | 17.5 |
| M18 | 2.50 | 18.00 | 15.50 | 15.50 | 20.0 |
| M20 | 2.50 | 20.00 | 17.50 | 17.50 | 22.0 |
| M22 | 2.50 | 22.00 | 19.50 | 19.50 | 24.0 |
| M24 | 3.00 | 24.00 | 21.00 | 21.00 | 26.0 |
| M27 | 3.00 | 27.00 | 24.00 | 24.00 | 29.0 |
| M30 | 3.50 | 30.00 | 26.50 | 26.50 | 32.0 |
| M33 | 3.50 | 33.00 | 29.50 | 29.50 | 35.0 |
| M36 | 4.00 | 36.00 | 32.00 | 32.00 | 38.0 |
| M39 | 4.00 | 39.00 | 35.00 | 35.00 | 41.0 |
| M42 | 4.50 | 42.00 | 37.50 | 37.50 | 44.0 |
| M45 | 4.50 | 45.00 | 40.50 | 40.50 | 47.0 |
| M48 | 5.00 | 48.00 | 43.00 | 43.00 | 50.0 |
| M52 | 5.00 | 52.00 | 47.00 | 47.00 | 54.0 |
| M56 | 5.50 | 56.00 | 50.50 | 50.50 | 58.0 |
| M60 | 5.50 | 60.00 | 54.50 | 54.50 | 62.0 |
| M64 | 6.00 | 64.00 | 58.00 | 58.00 | 66.0 |
| M68 | 6.00 | 68.00 | 62.00 | 62.00 | 70.0 |
ISO Metric Fine Thread Standards:
| Thread Size (M) | Pitch (mm) | Major Diameter (mm) | Minor Diameter (mm)* | Tapping Drill Size (mm) | Clearance Drill Size (Close Fit) |
|---|---|---|---|---|---|
| M6 × 0.75 | 0.75 | 6.00 | 5.15 | 5.25 | 6.2 |
| M8 × 0.75 | 0.75 | 8.00 | 7.10 | 7.20 | 8.2 |
| M8 × 1.00 | 1.00 | 8.00 | 6.84 | 7.00 | 8.2 |
| M10 × 0.75 | 0.75 | 10.00 | 9.10 | 9.20 | 10.2 |
| M10 × 1.00 | 1.00 | 10.00 | 8.84 | 9.00 | 10.2 |
| M10 × 1.25 | 1.25 | 10.00 | 8.50 | 8.75 | 10.2 |
| M12 × 1.00 | 1.00 | 12.00 | 10.84 | 11.00 | 12.2 |
| M12 × 1.25 | 1.25 | 12.00 | 10.60 | 10.75 | 12.2 |
| M12 × 1.50 | 1.50 | 12.00 | 10.27 | 10.50 | 12.2 |
| M14 × 1.00 | 1.00 | 14.00 | 12.84 | 13.00 | 14.2 |
| M14 × 1.25 | 1.25 | 14.00 | 12.60 | 12.75 | 14.2 |
| M14 × 1.50 | 1.50 | 14.00 | 12.27 | 12.50 | 14.2 |
| M16 × 1.00 | 1.00 | 16.00 | 14.84 | 15.00 | 16.2 |
| M16 × 1.50 | 1.50 | 16.00 | 14.27 | 14.50 | 16.2 |
| M16 × 2.00 | 2.00 | 16.00 | 13.73 | 14.00 | 16.2 |
| M18 × 1.50 | 1.50 | 18.00 | 16.27 | 16.50 | 18.2 |
| M18 × 2.00 | 2.00 | 18.00 | 15.73 | 16.00 | 18.2 |
| M20 × 1.50 | 1.50 | 20.00 | 18.27 | 18.50 | 20.2 |
| M20 × 2.00 | 2.00 | 20.00 | 17.73 | 18.00 | 20.2 |
| M22 × 1.50 | 1.50 | 22.00 | 20.27 | 20.50 | 22.2 |
| M24 × 2.00 | 2.00 | 24.00 | 21.73 | 22.00 | 24.2 |
| M27 × 2.00 | 2.00 | 27.00 | 24.73 | 25.00 | 27.2 |
| M30 × 2.00 | 2.00 | 30.00 | 27.73 | 28.00 | 30.2 |
| M33 × 2.00 | 2.00 | 33.00 | 30.73 | 31.00 | 33.2 |
| M36 × 3.00 | 3.00 | 36.00 | 32.90 | 33.00 | 36.2 |
| M39 × 3.00 | 3.00 | 39.00 | 35.90 | 36.00 | 39.2 |
| M42 × 3.00 | 3.00 | 42.00 | 38.90 | 39.00 | 42.2 |
| M45 × 3.00 | 3.00 | 45.00 | 41.90 | 42.00 | 45.2 |
| M48 × 3.00 | 3.00 | 48.00 | 44.90 | 45.00 | 48.2 |
| M52 × 3.00 | 3.00 | 52.00 | 48.90 | 49.00 | 52.2 |
| M56 × 4.00 | 4.00 | 56.00 | 51.90 | 52.00 | 56.2 |
| M60 × 4.00 | 4.00 | 60.00 | 55.90 | 56.00 | 60.2 |
| M64 × 4.00 | 4.00 | 64.00 | 59.90 | 60.00 | 64.2 |
British Association (B.A.) Thread Standards
Common Uses: Precision instruments, electrical components, and small mechanical devices.
Year Introduced: 1884
Thread Angle: 47.5°
Regions: Primarily the United Kingdom and countries with historical British influence.
B.A. Thread Dimensions:
| BA Size | Major Diameter (mm) | Pitch (mm) | Tapping Drill (mm) | Clearance Drill (mm) |
|---|---|---|---|---|
| 0 BA | 6.0 | 1.0 | 5.1 | 6.1 |
| 1 BA | 5.3 | 0.9 | 4.5 | 5.4 |
| 2 BA | 4.7 | 0.81 | 4.0 | 4.8 |
| 3 BA | 4.1 | 0.73 | 3.45 | 4.2 |
| 4 BA | 3.6 | 0.66 | 3.0 | 3.7 |
| 5 BA | 3.2 | 0.59 | 2.65 | 3.3 |
| 6 BA | 2.8 | 0.53 | 2.3 | 2.85 |
| 7 BA | 2.5 | 0.47 | 2.05 | 2.55 |
| 8 BA | 2.2 | 0.43 | 1.8 | 2.25 |
| 9 BA | 2.0 | 0.38 | 1.55 | 1.95 |
| 10 BA | 1.8 | 0.35 | 1.4 | 1.8 |
| 11 BA | 1.6 | 0.32 | 1.2 | 1.6 |
| 12 BA | 1.4 | 0.30 | 1.05 | 1.4 |
British Standard Fine (B.S.F.) Thread Standards
Common Uses: Automotive, aerospace, and machinery applications requiring fine threads.
Year Introduced: 1908
Thread Angle: 55°
Regions: United Kingdom and countries with historical British influence.
B.S.F. Thread Dimensions:
| Thread Size | TPI | Pitch (in) | Major Diameter (in) | Minor Diameter (in) | Tapping Drill Size (in) | Clearance Drill Size (in) |
|---|---|---|---|---|---|---|
| 3/16″ | 32 | 0.0313 | 0.1875 | 0.152 | #22 (0.1570) | 13/64 (0.2031) |
| 1/4″ | 26 | 0.0385 | 0.2500 | 0.210 | #10 (0.1935) | 17/64 (0.2656) |
| 5/16″ | 22 | 0.0455 | 0.3125 | 0.267 | Letter F (0.2570) | 21/64 (0.3281) |
| 3/8″ | 20 | 0.0500 | 0.3750 | 0.326 | Letter I (0.2720) | 25/64 (0.3906) |
| 7/16″ | 18 | 0.0556 | 0.4375 | 0.382 | 11/32 (0.3438) | 29/64 (0.4531) |
| 1/2″ | 16 | 0.0625 | 0.5000 | 0.440 | 27/64 (0.4219) | 17/32 (0.5313) |
| 9/16″ | 16 | 0.0625 | 0.5625 | 0.504 | 15/32 (0.4688) | 19/32 (0.5938) |
| 5/8″ | 14 | 0.0714 | 0.6250 | 0.559 | 17/32 (0.5313) | 21/32 (0.6563) |
| 11/16″ | 14 | 0.0714 | 0.6875 | 0.621 | 19/32 (0.5938) | 23/32 (0.7188) |
| 3/4″ | 12 | 0.0833 | 0.7500 | 0.676 | 21/32 (0.6563) | 25/32 (0.7813) |
| 7/8″ | 11 | 0.0909 | 0.8750 | 0.793 | 25/32 (0.7813) | 29/32 (0.9063) |
| 1″ | 10 | 0.1000 | 1.0000 | 0.910 | 7/8 (0.8750) | 1-1/16 (1.0625) |
| 1-1/8″ | 9 | 0.1111 | 1.1250 | 1.022 | 1 (1.0000) | 1-3/16 (1.1875) |
| 1-1/4″ | 9 | 0.1111 | 1.2500 | 1.147 | 1-1/8 (1.1250) | 1-5/16 (1.3125) |
| 1-3/8″ | 8 | 0.1250 | 1.3750 | 1.262 | 1-1/4 (1.2500) | 1-7/16 (1.4375) |
| 1-1/2″ | 8 | 0.1250 | 1.5000 | 1.387 | 1-3/8 (1.3750) | 1-9/16 (1.5625) |
| 1-5/8″ | 7 | 0.1429 | 1.6250 | 1.497 | 1-1/2 (1.5000) | 1-11/16 (1.6875) |
| 1-3/4″ | 7 | 0.1429 | 1.7500 | 1.622 | 1-5/8 (1.6250) | 1-13/16 (1.8125) |
| 1-7/8″ | 6 | 0.1667 | 1.8750 | 1.724 | 1-3/4 (1.7500) | 1-15/16 (1.9375) |
| 2″ | 6 | 0.1667 | 2.0000 | 1.849 | 1-7/8 (1.8750) | 2-1/16 (2.0625) |
| 2-1/4″ | 5 | 0.2000 | 2.2500 | 2.074 | 2-1/8 (2.1250) | 2-5/16 (2.3125) |
| 2-1/2″ | 5 | 0.2000 | 2.5000 | 2.324 | 2-3/8 (2.3750) | 2-9/16 (2.5625) |
| 2-3/4″ | 4.5 | 0.2222 | 2.7500 | 2.547 | 2-5/8 (2.6250) | 2-13/16 (2.8125) |
| 3″ | 4.5 | 0.2222 | 3.0000 | 2.797 | 2-7/8 (2.8750) | 3-1/16 (3.0625) |
British Standard Whitworth (B.S.W.) Thread Standards
Common Uses: General engineering and construction applications.
Year Introduced: 1841
Thread Angle: 55°
Regions: United Kingdom and countries with historical British influence.
B.S.W. Thread Dimensions (Extended):
| Thread Size | TPI | Pitch (in) | Major Diameter (in) | Minor Diameter (in) | Tapping Drill Size (in) | Clearance Drill Size (in) |
|---|---|---|---|---|---|---|
| 1/8″ | 40 | 0.0250 | 0.1250 | 0.0930 | #38 (0.1015) | 9/64 (0.1406) |
| 3/16″ | 24 | 0.0417 | 0.1875 | 0.1340 | #27 (0.1440) | 13/64 (0.2031) |
| 1/4″ | 20 | 0.0500 | 0.2500 | 0.1860 | #9 (0.1960) | 17/64 (0.2656) |
| 5/16″ | 18 | 0.0556 | 0.3125 | 0.2410 | 1/4 (0.2500) | 21/64 (0.3281) |
| 3/8″ | 16 | 0.0625 | 0.3750 | 0.2950 | 5/16 (0.3125) | 25/64 (0.3906) |
| 7/16″ | 14 | 0.0714 | 0.4375 | 0.3460 | U (0.3680) | 29/64 (0.4531) |
| 1/2″ | 12 | 0.0833 | 0.5000 | 0.3930 | 27/64 (0.4219) | 17/32 (0.5313) |
| 9/16″ | 12 | 0.0833 | 0.5625 | 0.4560 | 15/32 (0.4688) | 19/32 (0.5938) |
| 5/8″ | 11 | 0.0909 | 0.6250 | 0.5090 | 17/32 (0.5313) | 21/32 (0.6563) |
| 11/16″ | 11 | 0.0909 | 0.6875 | 0.5710 | 19/32 (0.5938) | 23/32 (0.7188) |
| 3/4″ | 10 | 0.1000 | 0.7500 | 0.6220 | 21/32 (0.6563) | 25/32 (0.7813) |
| 7/8″ | 9 | 0.1111 | 0.8750 | 0.7330 | 49/64 (0.7656) | 29/32 (0.9063) |
| 1″ | 8 | 0.1250 | 1.0000 | 0.8400 | 7/8 (0.8750) | 1-1/16 (1.0625) |
| 1-1/8″ | 7 | 0.1429 | 1.1250 | 0.9500 | 1 (1.0000) | 1-3/16 (1.1875) |
| 1-1/4″ | 7 | 0.1429 | 1.2500 | 1.0750 | 1-1/8 (1.1250) | 1-5/16 (1.3125) |
| 1-3/8″ | 6 | 0.1667 | 1.3750 | 1.1760 | 1-1/4 (1.2500) | 1-7/16 (1.4375) |
| 1-1/2″ | 6 | 0.1667 | 1.5000 | 1.3010 | 1-3/8 (1.3750) | 1-9/16 (1.5625) |
| 1-5/8″ | 5 | 0.2000 | 1.6250 | 1.4010 | 1-1/2 (1.5000) | 1-11/16 (1.6875) |
| 1-3/4″ | 5 | 0.2000 | 1.7500 | 1.5260 | 1-5/8 (1.6250) | 1-13/16 (1.8125) |
| 2″ | 4.5 | 0.2222 | 2.0000 | 1.7460 | 1-7/8 (1.8750) | 2-1/16 (2.0625) |
British Standard Pipe (B.S.P.) Thread Standards
Common Uses: Plumbing, gas fittings, and fluid transfer systems.
Year Introduced: 1905
Thread Angle: 55°
Regions: United Kingdom, Europe, Australia, and other countries using the metric system.
B.S.P. Thread Dimensions:
| Size | TPI | Major Diameter (mm) | Minor Diameter (mm) | Tapping Drill Size (mm) |
|---|---|---|---|---|
| 1/8″ | 28 | 9.728 | 8.566 | 8.70 |
| 1/4″ | 19 | 13.157 | 11.445 | 11.60 |
| 3/8″ | 19 | 16.662 | 14.950 | 15.00 |
| 1/2″ | 14 | 20.955 | 18.631 | 19.00 |
| 5/8″ | 14 | 22.911 | 20.587 | 20.75 |
| 3/4″ | 14 | 26.441 | 24.117 | 24.50 |
| 7/8″ | 14 | 30.201 | 27.877 | 28.00 |
| 1″ | 11 | 33.249 | 31.770 | 30.50 |
| 1-1/4″ | 11 | 41.910 | 38.952 | 39.50 |
| 1-1/2″ | 11 | 47.803 | 44.845 | 45.00 |
| 2″ | 11 | 59.614 | 56.656 | 57.00 |
Unified National Coarse (U.N.C.) Thread Standards
Introduced: 1949 (Unified Thread Standard agreement between the U.S., U.K., and Canada)
Thread Angle: 60°
Common Use: General-purpose bolts, nuts, screws, and industrial fasteners. Widely used in construction, automotive, and machinery industries.
Most Common Regions: United States, Canada, and other countries using imperial/SAE systems.
| Thread Size | TPI | Major Diameter (in) | Minor Diameter (in)* | Pitch (in) | Tapping Drill Size (in) | Clearance Drill Size (in) |
|---|---|---|---|---|---|---|
| 1/4″-20 | 20 | 0.2500 | 0.1877 | 0.0500 | #7 (0.2010) | 17/64 (0.2656) |
| 5/16″-18 | 18 | 0.3125 | 0.2406 | 0.0556 | F (0.2570) | 21/64 (0.3281) |
| 3/8″-16 | 16 | 0.3750 | 0.2974 | 0.0625 | 5/16 (0.3125) | 13/32 (0.4063) |
| 7/16″-14 | 14 | 0.4375 | 0.3495 | 0.0714 | U (0.3680) | 29/64 (0.4531) |
| 1/2″-13 | 13 | 0.5000 | 0.4019 | 0.0769 | 27/64 (0.4219) | 17/32 (0.5313) |
| 9/16″-12 | 12 | 0.5625 | 0.4565 | 0.0833 | 15/32 (0.4688) | 19/32 (0.5938) |
| 5/8″-11 | 11 | 0.6250 | 0.5092 | 0.0909 | 17/32 (0.5313) | 21/32 (0.6563) |
| 3/4″-10 | 10 | 0.7500 | 0.6175 | 0.1000 | 21/32 (0.6563) | 25/32 (0.7813) |
| 7/8″-9 | 9 | 0.8750 | 0.7251 | 0.1111 | 25/32 (0.7813) | 29/32 (0.9063) |
| 1″-8 | 8 | 1.0000 | 0.8374 | 0.1250 | 7/8 (0.8750) | 1-1/16 (1.0625) |
| 1-1/8″-7 | 7 | 1.1250 | 0.9449 | 0.1429 | 1 (1.0000) | 1-3/16 (1.1875) |
| 1-1/4″-7 | 7 | 1.2500 | 1.0699 | 0.1429 | 1-1/8 (1.1250) | 1-5/16 (1.3125) |
| 1-3/8″-6 | 6 | 1.3750 | 1.1732 | 0.1667 | 1-1/4 (1.2500) | 1-7/16 (1.4375) |
| 1-1/2″-6 | 6 | 1.5000 | 1.2982 | 0.1667 | 1-3/8 (1.3750) | 1-9/16 (1.5625) |
| 1-5/8″-5 | 5 | 1.6250 | 1.3995 | 0.2000 | 1-1/2 (1.5000) | 1-11/16 (1.6875) |
| 1-3/4″-5 | 5 | 1.7500 | 1.5245 | 0.2000 | 1-5/8 (1.6250) | 1-13/16 (1.8125) |
| 1-7/8″-4.5 | 4.5 | 1.8750 | 1.6189 | 0.2222 | 1-3/4 (1.7500) | 1-15/16 (1.9375) |
| 2″-4.5 | 4.5 | 2.0000 | 1.7439 | 0.2222 | 1-7/8 (1.8750) | 2-1/16 (2.0625) |
Unified National Fine (U.N.F.) Thread Standards
Introduced: 1949 (with U.N.C. as part of the Unified Thread Standard)
Thread Angle: 60°
Common Use: High-stress, high-precision applications like automotive, aerospace, and machinery where vibration resistance is important.
Regions: United States, Canada, and countries using SAE standards.
UNF Thread Dimensions
| Thread Size | TPI | Major Diameter (in) | Minor Diameter (in)* | Pitch (in) | Tapping Drill Size (in) | Clearance Drill Size (in) |
|---|---|---|---|---|---|---|
| 1/4″-28 | 28 | 0.2500 | 0.2130 | 0.0357 | #3 (0.2130) | 17/64 (0.2656) |
| 5/16″-24 | 24 | 0.3125 | 0.2710 | 0.0417 | I (0.2720) | 21/64 (0.3281) |
| 3/8″-24 | 24 | 0.3750 | 0.3340 | 0.0417 | Q (0.3320) | 13/32 (0.4063) |
| 7/16″-20 | 20 | 0.4375 | 0.3870 | 0.0500 | 25/64 (0.3906) | 29/64 (0.4531) |
| 1/2″-20 | 20 | 0.5000 | 0.4500 | 0.0500 | 29/64 (0.4531) | 17/32 (0.5313) |
| 9/16″-18 | 18 | 0.5625 | 0.5100 | 0.0556 | 15/32 (0.4688) | 19/32 (0.5938) |
| 5/8″-18 | 18 | 0.6250 | 0.5730 | 0.0556 | 37/64 (0.5781) | 21/32 (0.6563) |
| 3/4″-16 | 16 | 0.7500 | 0.6880 | 0.0625 | 11/16 (0.6875) | 25/32 (0.7813) |
| 7/8″-14 | 14 | 0.8750 | 0.8020 | 0.0714 | 13/16 (0.8125) | 29/32 (0.9063) |
| 1″-12 | 12 | 1.0000 | 0.9170 | 0.0833 | 59/64 (0.9219) | 1-1/16 (1.0625) |
| 1-1/8″-12 | 12 | 1.1250 | 1.0420 | 0.0833 | 1-3/64 (1.0469) | 1-3/16 (1.1875) |
| 1-1/4″-12 | 12 | 1.2500 | 1.1670 | 0.0833 | 1-5/32 (1.1563) | 1-5/16 (1.3125) |
| 1-3/8″-12 | 12 | 1.3750 | 1.2920 | 0.0833 | 1-9/32 (1.2813) | 1-7/16 (1.4375) |
| 1-1/2″-12 | 12 | 1.5000 | 1.4170 | 0.0833 | 1-13/32 (1.4063) | 1-9/16 (1.5625) |
American National Coarse (A.N.C.) Thread Standards
Introduced: Early 20th century (Standardized by ANSI before 1949), ANC have now been replaced with UNC.
Thread Angle: 60°
Common Use: Machinery, construction, and industrial fasteners prior to the Unified Thread Standard
Regions: United States (legacy use)
A.N.C. Thread Dimensions
| Thread Size | TPI | Major Diameter (in) | Minor Diameter (in)* | Pitch (in) | Tapping Drill Size (in) | Clearance Drill Size (in) |
|---|---|---|---|---|---|---|
| 1/4″-20 | 20 | 0.2500 | 0.1877 | 0.0500 | #7 (0.2010) | 17/64 (0.2656) |
| 5/16″-18 | 18 | 0.3125 | 0.2406 | 0.0556 | F (0.2570) | 21/64 (0.3281) |
| 3/8″-16 | 16 | 0.3750 | 0.2974 | 0.0625 | 5/16 (0.3125) | 13/32 (0.4063) |
| 7/16″-14 | 14 | 0.4375 | 0.3495 | 0.0714 | U (0.3680) | 29/64 (0.4531) |
| 1/2″-13 | 13 | 0.5000 | 0.4019 | 0.0769 | 27/64 (0.4219) | 17/32 (0.5313) |
| 9/16″-12 | 12 | 0.5625 | 0.4565 | 0.0833 | 15/32 (0.4688) | 19/32 (0.5938) |
| 5/8″-11 | 11 | 0.6250 | 0.5092 | 0.0909 | 17/32 (0.5313) | 21/32 (0.6563) |
| 3/4″-10 | 10 | 0.7500 | 0.6175 | 0.1000 | 21/32 (0.6563) | 25/32 (0.7813) |
| 7/8″-9 | 9 | 0.8750 | 0.7251 | 0.1111 | 25/32 (0.7813) | 29/32 (0.9063) |
| 1″-8 | 8 | 1.0000 | 0.8374 | 0.1250 | 7/8 (0.8750) | 1-1/16 (1.0625) |
| 1-1/8″-7 | 7 | 1.1250 | 0.9449 | 0.1429 | 1 (1.0000) | 1-3/16 (1.1875) |
| 1-1/4″-7 | 7 | 1.2500 | 1.0699 | 0.1429 | 1-1/8 (1.1250) | 1-5/16 (1.3125) |
| 1-3/8″-6 | 6 | 1.3750 | 1.1732 | 0.1667 | 1-1/4 (1.2500) | 1-7/16 (1.4375) |
| 1-1/2″-6 | 6 | 1.5000 | 1.2982 | 0.1667 | 1-3/8 (1.3750) | 1-9/16 (1.5625) |
| 1-5/8″-5 | 5 | 1.6250 | 1.3995 | 0.2000 | 1-1/2 (1.5000) | 1-11/16 (1.6875) |
| 1-3/4″-5 | 5 | 1.7500 | 1.5245 | 0.2000 | 1-5/8 (1.6250) | 1-13/16 (1.8125) |
| 1-7/8″-4.5 | 4.5 | 1.8750 | 1.6189 | 0.2222 | 1-3/4 (1.7500) | 1-15/16 (1.9375) |
| 2″-4.5 | 4.5 | 2.0000 | 1.7439 | 0.2222 | 1-7/8 (1.8750) | 2-1/16 (2.0625) |
American National Fine (A.N.F.) Thread Standards
Introduced: Thread standards introduced early in the 20th century (Standardized by ANSI before 1949) ANF threads have now been replaced by U.N.F.
Thread Angle: 60°
Common Use: Precision assemblies, fine adjustment mechanisms, and aviation applications
Regions: United States (legacy use)
A.N.F. Thread Dimensions
| Thread Size | TPI | Major Diameter (in) | Minor Diameter (in)* | Pitch (in) | Tapping Drill Size (in) | Clearance Drill Size (in) |
|---|---|---|---|---|---|---|
| 1/4″-28 | 28 | 0.2500 | 0.2130 | 0.0357 | #3 (0.2130) | 17/64 (0.2656) |
| 5/16″-24 | 24 | 0.3125 | 0.2710 | 0.0417 | I (0.2720) | 21/64 (0.3281) |
| 3/8″-24 | 24 | 0.3750 | 0.3340 | 0.0417 | Q (0.3320) | 13/32 (0.4063) |
| 7/16″-20 | 20 | 0.4375 | 0.3870 | 0.0500 | 25/64 (0.3906) | 29/64 (0.4531) |
| 1/2″-20 | 20 | 0.5000 | 0.4500 | 0.0500 | 29/64 (0.4531) | 17/32 (0.5313) |
| 9/16″-18 | 18 | 0.5625 | 0.5100 | 0.0556 | 15/32 (0.4688) | 19/32 (0.5938) |
| 5/8″-18 | 18 | 0.6250 | 0.5730 | 0.0556 | 37/64 (0.5781) | 21/32 (0.6563) |
| 3/4″-16 | 16 | 0.7500 | 0.6880 | 0.0625 | 11/16 (0.6875) | 25/32 (0.7813) |
| 7/8″-14 | 14 | 0.8750 | 0.8020 | 0.0714 | 13/16 (0.8125) | 29/32 (0.9063) |
| 1″-12 | 12 | 1.0000 | 0.9170 | 0.0833 | 59/64 (0.9219) | 1-1/16 (1.0625) |
| 1-1/8″-12 | 12 | 1.1250 | 1.0420 | 0.0833 | 1-3/64 (1.0469) | 1-3/16 (1.1875) |
| 1-1/4″-12 | 12 | 1.2500 | 1.1670 | 0.0833 | 1-5/32 (1.1563) | 1-5/16 (1.3125) |
| 1-3/8″-12 | 12 | 1.3750 | 1.2920 | 0.0833 | 1-9/32 (1.2813) | 1-7/16 (1.4375) |
| 1-1/2″-12 | 12 | 1.5000 | 1.4170 | 0.0833 | 1-13/32 (1.4063) | 1-9/16 (1.5625) |
If you would like to discuss a project with us please get in touch or book a consultation.