Tap & Drill Size Chart
Unified National (Inch) Taps
| Tap Size | TPI | Major Dia (in) | 75% Drill | 50% Drill | Close Fit Drill |
|---|
| #0-80 | 80 | .0600 | 3/64 | 55 | 52 |
| #1-64 | 64 | .0730 | 53 | 1/16 | 48 |
| #1-72 | 72 | .0730 | 53 | 52 | 48 |
| #2-56 | 56 | .0860 | 50 | 49 | 43 |
| #2-64 | 64 | .0860 | 50 | 48 | 43 |
| #3-48 | 48 | .0990 | 47 | 44 | 37 |
| #4-40 | 40 | .1120 | 43 | 41 | 32 |
| #4-48 | 48 | .1120 | 42 | 40 | 32 |
| #5-40 | 40 | .1250 | 38 | 35 | 30 |
| #5-44 | 44 | .1250 | 37 | 34 | 30 |
| #6-32 | 32 | .1380 | 36 | 32 | 27 |
| #6-40 | 40 | .1380 | 33 | 31 | 27 |
| #8-32 | 32 | .1640 | 29 | 27 | 18 |
| #8-36 | 36 | .1640 | 29 | 26 | 18 |
| #10-24 | 24 | .1900 | 25 | 20 | 9 |
| #10-32 | 32 | .1900 | 21 | 16 | 9 |
| #12-24 | 24 | .2160 | 16 | 12 | 2 |
| #12-28 | 28 | .2160 | 14 | 10 | 2 |
| 1/4-20 | 20 | .2500 | #7 | #3 | F |
| 1/4-28 | 28 | .2500 | #3 | 1 | F |
| 5/16-18 | 18 | .3125 | F | J | Q |
| 5/16-24 | 24 | .3125 | I | K | Q |
| 3/8-16 | 16 | .3750 | 5/16 | T | W |
| 3/8-24 | 24 | .3750 | Q | S | W |
| 7/16-14 | 14 | .4375 | U | 25/64 | 29/64 |
| 7/16-20 | 20 | .4375 | 25/64 | 13/32 | 29/64 |
| 1/2-13 | 13 | .5000 | 27/64 | 29/64 | 33/64 |
| 1/2-20 | 20 | .5000 | 29/64 | 15/32 | 33/64 |
| 9/16-12 | 12 | .5625 | 31/64 | 33/64 | 37/64 |
| 9/16-18 | 18 | .5625 | 33/64 | 17/32 | 37/64 |
| 5/8-11 | 11 | .6250 | 17/32 | 9/16 | 41/64 |
| 5/8-18 | 18 | .6250 | 37/64 | 19/32 | 41/64 |
| 3/4-10 | 10 | .7500 | 21/32 | 11/16 | 49/64 |
| 3/4-16 | 16 | .7500 | 11/16 | 45/64 | 49/64 |
| 7/8-9 | 9 | .8750 | 49/64 | 51/64 | 57/64 |
| 7/8-14 | 14 | .8750 | 13/16 | 53/64 | 57/64 |
| 1-8 | 8 | 1.0000 | 7/8 | 59/64 | 1-1/64 |
| 1-12 | 12 | 1.0000 | 15/16 | 61/64 | 1-1/64 |
Metric Taps
| Tap Size | Pitch (mm) | Major Dia (mm) | 75% Drill (mm) | Close Fit Drill (mm) |
|---|
| M1.6×0.35 | 0.35 | 1.60 | 1.25 | 1.70 |
| M2×0.4 | 0.40 | 2.00 | 1.60 | 2.10 |
| M2.5×0.45 | 0.45 | 2.50 | 2.05 | 2.65 |
| M3×0.5 | 0.50 | 3.00 | 2.50 | 3.15 |
| M4×0.7 | 0.70 | 4.00 | 3.30 | 4.20 |
| M5×0.8 | 0.80 | 5.00 | 4.20 | 5.25 |
| M6×1.0 | 1.00 | 6.00 | 5.00 | 6.30 |
| M8×1.25 | 1.25 | 8.00 | 6.75 | 8.40 |
| M10×1.5 | 1.50 | 10.00 | 8.50 | 10.50 |
| M12×1.75 | 1.75 | 12.00 | 10.20 | 12.50 |
| M14×2.0 | 2.00 | 14.00 | 12.00 | 14.50 |
| M16×2.0 | 2.00 | 16.00 | 14.00 | 16.50 |
| M18×2.5 | 2.50 | 18.00 | 15.50 | 18.50 |
| M20×2.5 | 2.50 | 20.00 | 17.50 | 20.50 |
| M22×2.5 | 2.50 | 22.00 | 19.50 | 22.50 |
| M24×3.0 | 3.00 | 24.00 | 21.00 | 24.50 |
Pipe Taps (NPT)
| Pipe Size | TPI | Tap Drill |
|---|
| 1/8 | 27 | 21/64 |
| 1/4 | 18 | 7/16 |
| 3/8 | 18 | 37/64 |
| 1/2 | 14 | 23/32 |
| 3/4 | 14 | 59/64 |
| 1 | 11-1/2 | 1-5/32 |
| 1-1/4 | 11-1/2 | 1-1/2 |
| 1-1/2 | 11-1/2 | 1-47/64 |
| 2 | 11-1/2 | 2-7/32 |
Disclaimer
The content on this page is provided for educational and quick-reference purposes only. It is not a substitute for manufacturer specifications, tooling documentation, or professional machining guidance. Always verify feeds, speeds, and tooling recommendations for your specific setup, machine, and material before machining. machref.com makes no warranty regarding the accuracy or completeness of this information. See our Terms of Service, Privacy Policy, and Accessibility Statement.