Tap Drill Chart
| Tap | Drill | Inch | mm | Std |
|---|---|---|---|---|
| #4-40 | #43 | 0.0890 | 2.26 | UNC |
| #6-32 | #36 | 0.1065 | 2.71 | UNC |
| #8-32 | #29 | 0.1360 | 3.45 | UNC |
| #10-24 | #25 | 0.1495 | 3.80 | UNC |
| 1/4-20 | #7 | 0.2010 | 5.11 | UNC |
| 5/16-18 | F | 0.2570 | 6.53 | UNC |
| 3/8-16 | 5/16 | 0.3125 | 7.94 | UNC |
| 7/16-14 | U | 0.3680 | 9.35 | UNC |
| 1/2-13 | 27/64 | 0.4219 | 10.72 | UNC |
| 5/8-11 | 17/32 | 0.5312 | 13.49 | UNC |
| 3/4-10 | 21/32 | 0.6562 | 16.67 | UNC |
| 1-8 | 7/8 | 0.8750 | 22.23 | UNC |
| #4-48 | #42 | 0.0935 | 2.37 | UNF |
| #6-40 | #33 | 0.1130 | 2.87 | UNF |
| #8-36 | #29 | 0.1360 | 3.45 | UNF |
| #10-32 | #21 | 0.1590 | 4.04 | UNF |
| 1/4-28 | #3 | 0.2130 | 5.41 | UNF |
| 5/16-24 | I | 0.2720 | 6.91 | UNF |
| 3/8-24 | Q | 0.3320 | 8.43 | UNF |
| 7/16-20 | 25/64 | 0.3906 | 9.92 | UNF |
| 1/2-20 | 29/64 | 0.4531 | 11.51 | UNF |
| 5/8-18 | 37/64 | 0.5781 | 14.68 | UNF |
| 3/4-16 | 11/16 | 0.6875 | 17.46 | UNF |
| M2×0.4 | 1.6 mm | 0.0630 | 1.60 | ISO |
| M2.5×0.45 | 2.05 mm | 0.0807 | 2.05 | ISO |
| M3×0.5 | 2.5 mm | 0.0984 | 2.50 | ISO |
| M4×0.7 | 3.3 mm | 0.1299 | 3.30 | ISO |
| M5×0.8 | 4.2 mm | 0.1654 | 4.20 | ISO |
| M6×1.0 | 5.0 mm | 0.1969 | 5.00 | ISO |
| M8×1.25 | 6.8 mm | 0.2677 | 6.80 | ISO |
| M10×1.5 | 8.5 mm | 0.3346 | 8.50 | ISO |
| M12×1.75 | 10.2 mm | 0.4016 | 10.20 | ISO |
| M14×2.0 | 12.0 mm | 0.4724 | 12.00 | ISO |
| M16×2.0 | 14.0 mm | 0.5512 | 14.00 | ISO |
| M20×2.5 | 17.5 mm | 0.6890 | 17.50 | ISO |
75% thread engagement — the shop standard. Going to 100% (theoretical max) means smaller drill = more torque on the tap = broken taps. Drop to 65% if your material is hard or the tap is small. Click any row to copy the full spec.
Pairs well with
TD
About Tap Drill Chart
UNC, UNF, and ISO metric tap-drill sizes at 75% thread engagement.
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