This 4-minute video will give you the essential info required to cut threads and keep yourself from getting into trouble.
Both Imperial and Metric tap drill bit sizes are charted below.
If you need a tap and die set on the cheap, get the Harbor Freight Set(s). We’ve had our current 45 pc SAE and Metric sets (~$85 each) in regular shop use for better than four years now. We’ve lost a couple, but haven’t broken any. With proper cutting fluid use, they’ve stayed sharper than expected.
Alternately, Amazon offers several affordable Tap and Die set options.
Tap Drill Chart and Reference
Imperial Tap Drill Chart | |||||||||||
| Machine Screw Size | Number of Threads Per Inch | Minor Dia. | Tap Drills | Clearance Hole Drills | |||||||
| Aluminum, Brass & Plastics 75% Thread | Stainless Steel, Steels & Iron 50% Thread | All Materials | |||||||||
| Close Fit | Free Fit | ||||||||||
| No. or Dia. | Major Dia. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | ||
| 0 | .0600 | 80 | .0447 | 3/64 | .0469 | 55 | .0520 | 52 | .0635 | 50 | .0700 |
| 1 | .0730 | 64 | .0538 | 53 | .0595 | 1/16 | .0625 | 48 | .0760 | 46 | .0810 |
| 72 | .0560 | 53 | .0595 | 52 | .0635 | ||||||
| 2 | .0860 | 56 | .0641 | 50 | .0700 | 49 | .0730 | 43 | .0890 | 41 | .0960 |
| 64 | .0668 | 50 | .0700 | 48 | .0760 | ||||||
| 3 | .0990 | 48 | .0734 | 47 | .0785 | 44 | .0860 | 37 | .1040 | 35 | .1100 |
| 56 | .0771 | 45 | .0820 | 43 | .0890 | ||||||
| 4 | .1120 | 40 | .0813 | 43 | .0890 | 41 | .0960 | 32 | .1160 | 30 | .1285 |
| 48 | .0864 | 42 | .0935 | 40 | .0980 | ||||||
| 5 | .1250 | 40 | .0943 | 38 | .1015 | 7/64 | .1094 | 30 | .1285 | 29 | .1360 |
| 44 | .0971 | 37 | .1040 | 35 | .1100 | ||||||
| 6 | .1380 | 32 | .0997 | 36 | .1065 | 32 | .1160 | 27 | .1440 | 25 | .1495 |
| 40 | .1073 | 33 | .1130 | 31 | .1200 | ||||||
| 8 | .1640 | 32 | .1257 | 29 | .1360 | 27 | .1440 | 18 | .1695 | 16 | .1770 |
| 36 | .1299 | 29 | .1360 | 26 | .1470 | ||||||
| 10 | .1900 | 24 | .1389 | 25 | .1495 | 20 | .1610 | 9 | .1960 | 7 | .2010 |
| 32 | .1517 | 21 | .1590 | 18 | .1695 | ||||||
| 12 | .2160 | 24 | .1649 | 16 | .1770 | 12 | .1890 | 2 | .2210 | 1 | .2280 |
| 28 | .1722 | 14 | .1820 | 10 | .1935 | ||||||
| 32 | .1777 | 13 | .1850 | 9 | .1960 | ||||||
| 1/4 | .2500 | 20 | .1887 | 7 | .2010 | 7/32 | .2188 | F | .2570 | H | .2660 |
| 28 | .2062 | 3 | .2130 | 1 | .2280 | ||||||
| 32 | .2117 | 7/32 | .2188 | 1 | .2280 | ||||||
| 5/16 | .3125 | 18 | .2443 | F | .2570 | J | .2770 | P | .3230 | Q | .3320 |
| 24 | .2614 | I | .2720 | 9/32 | .2812 | ||||||
| 32 | .2742 | 9/32 | .2812 | L | .2900 | ||||||
| 3/8 | .3750 | 16 | .2983 | 5/16 | .3125 | Q | .3320 | W | .3860 | X | .3970 |
| 24 | .3239 | Q | .3320 | S | .3480 | ||||||
| 32 | .3367 | 11/32 | .3438 | T | .3580 | ||||||
7/16 | .4375 | 14 | .3499 | U | .3680 | 25/64 | .3906 | 29/64 | .4531 | 15/32 | .4687 |
| 20 | .3762 | 25/64 | .3906 | 13/32 | .4062 | ||||||
| 28 | .3937 | Y | .4040 | Z | .4130 | ||||||
| 1/2 | .5000 | 13 | .4056 | 27/64 | .4219 | 29/64 | .4531 | 33/64 | .5156 | 17/32 | .5312 |
| 20 | .4387 | 29/64 | .4531 | 15/32 | .4688 | ||||||
| 28 | .4562 | 15/32 | .4688 | 15/32 | .4688 | ||||||
| 9/16 | .5625 | 12 | .4603 | 31/64 | .4844 | 33/64 | .5156 | 37/64 | .5781 | 19/32 | .5938 |
| 18 | .4943 | 33/64 | .5156 | 17/32 | .5312 | ||||||
| 24 | .5114 | 33/64 | .5156 | 17/32 | .5312 | ||||||
| 5/8 | .6250 | 11 | .5135 | 17/32 | .5312 | 9/16 | .5625 | 41/64 | .6406 | 21/32 | .6562 |
| 18 | .5568 | 37/64 | .5781 | 19/32 | .5938 | ||||||
| 24 | .5739 | 37/64 | .5781 | 19/32 | .5938 | ||||||
| 11/16 | .6875 | 24 | .6364 | 41/64 | .6406 | 21/32 | .6562 | 45/64 | .7031 | 23/32 | .7188 |
3/4 | .7500 | 10 | .6273 | 21/32 | .6562 | 11/16 | .6875 | 49/64 | .7656 | 25/32 | .7812 |
| 16 | .6733 | 11/16 | .6875 | 45/64 | .7031 | ||||||
| 20 | .6887 | 45/64 | .7031 | 23/32 | .7188 | ||||||
| 1-3/16 | .8125 | 20 | .7512 | 49/64 | .7656 | 25/32 | .7812 | 53/64 | .8281 | 27/32 | .8438 |
| 7/8 | .8750 | 9 | .7387 | 49/64 | .7656 | 51/64 | .7969 | 57/64 | .8906 | 29/32 | .9062 |
| 14 | .7874 | 13/16 | .8125 | 53/64 | .8281 | ||||||
| 20 | .8137 | 53/64 | .8281 | 27/32 | .8438 | ||||||
| 15/16 | .9375 | 20 | .8762 | 57/64 | .8906 | 29/32 | .9062 | 61/64 | .9531 | 31/32 | .9688 |
| 1 | 1.000 | 8 | .8466 | 7/8 | .8750 | 59/64 | .9219 | 1-1/64 | 1.0156 | 1-1/32 | 1.0313 |
| 12 | .8978 | 15/16 | .9375 | 61/64 | .9531 | ||||||
| 20 | .9387 | 61/64 | .9531 | 31/32 | .9688 | ||||||
| 1-1/16 | 1.0625 | 18 | .9943 | 1.000 | 1.000 | 1-1/64 | 1.0156 | 1-5/64 | 1.0781 | 1-3/32 | 1.0938 |
| 1-1/8 | 1.1250 | 7 | .9497 | 63/64 | .9844 | 1-1/32 | 1.0313 | 1-9/64 | 1.1406 | 1-5/32 | 1.1562 |
| 12 | 1.0228 | 1-3/64 | 1.0469 | 1-5/64 | 1.0781 | ||||||
| 18 | 1.0568 | 1-1/16 | 1.0625 | 1-5/64 | 1.0781 | ||||||
| 1-3/16 | 1.1875 | 18 | 1.1193 | 1-1/8 | 1.1250 | 1-9/64 | 1.1406 | 1-13/64 | 1.2031 | 1-7/32 | 1.2188 |
1-1/4 | 1.2500 | 7 | 1.0747 | 1-7/64 | 1.1094 | 1-5/32 | 1.1562 | 1-17/64 | 1.2656 | 1-9/32 | 1.2812 |
| 12 | 1.1478 | 1-11/64 | 1.1719 | 1-13/64 | 1.2031 | ||||||
| 18 | 1.1818 | 1-3/16 | 1.1875 | 1-13/64 | 1.2031 | ||||||
| 1-5/16 | 1.3125 | 18 | 1.2443 | 1-1/4 | 1.2500 | 1-17/64 | 1.2656 | 1-21/64 | 1.3281 | 1-11/32 | 1.3438 |
| 1-3/8 | 1.3750 | 6 | 1.1705 | 1-7/32 | 1.2187 | 1-17/64 | 1.2656 | 1-25/64 | 1.3906 | 1-13/32 | 1.4062 |
| 12 | 1.2728 | 1-19/64 | 1.2969 | 1-21/64 | 1.3281 | ||||||
| 18 | 1.3068 | 1-5/16 | 1.3125 | 1-21/64 | 1.3281 | ||||||
| 1-7/16 | 1.4375 | 18 | 1.3693 | 1-3/8 | 1.3750 | 1-25/64 | 1.3906 | 1-29/64 | 1.4531 | 1-15/32 | 1.4688 |
| 1-1/2 | 1.500 | 6 | 1.2955 | 1-11/32 | 1.3437 | 1-25/64 | 1.3906 | 1-33/64 | 1.5156 | 1-17/32 | 1.5312 |
| 12 | 1.3978 | 1-27/64 | 1.4219 | 1-7/16 | 1.4375 | ||||||
| 18 | 1.4318 | 1-7/16 | 1.4375 | 1-29/64 | 1.4531 | ||||||
| 1-9/16 | 1.5625 | 18 | 1.4943 | 1-12 | 1.500 | 1-33/64 | 1.5156 | 1-37/64 | 1.5781 | 1-19/32 | 1.5938 |
| 1-5/8 | 1.625 | 18 | 1.5568 | 1-9/16 | 1.5625 | 1-37/64 | 1.5781 | 1-41/64 | 1.6406 | 1-21/32 | 1.6562 |
| 1-11/16 | 1.6875 | 18 | 1.6193 | 1-5/8 | 1.6250 | 1-41/64 | 1.6406 | 1-45/64 | 1.7031 | 1-23/32 | 1.7188 |
| 1-3/4 | 1.750 | 5 | 1.5046 | 1-9/16 | 1.5625 | 1-5/8 | 1.6250 | 1-49/64 | 1.7659 | 1-25/32 | 1.7812 |
Metric Tap Drill Chart | ||||||
| Tap size | Major Dia (mm) | Threads per | Tap Drill (mm) | Tap Drill (inch) | Clearance (mm) | Clearance (inch) |
| M1.6×0.35 | 1.6 | 0.35 | 1.25 | #55 | 1.8 | #49 |
| M2x0.4 | 2.0 | 0.40 | 1.60 | #52 | 2.4 | #41 |
| M2.5×0.45 | 2.5 | 0.45 | 2.05 | #46 | 2.9 | #32 |
| M3x.05 | 3.0 | 0.50 | 2.50 | #39 | 3.4 | #29 |
| M3.5×0.6 | 3.5 | 0.60 | 2.90 | #32 | 3.9 | #23 |
| M4x0.7 | 4.0 | 0.70 | 3.30 | #30 | 4.5 | #16 |
| M5x0.8 | 5.0 | 0.80 | 4.20 | #19 | 5.5 | 7/32 |
| M6x1 | 6.0 | 1.00 | 5.0 | #8 | 6.6 | G |
| M8x1.25 | 8.0 | 1.25 | 6.8 | H | 9.0 | T |
| M8x1 | 8.0 | 1.00 | 7.0 | J | 9.0 | T |
| M10x1.5 | 10.0 | 1.50 | 8.5 | R | 12.0 | 31/64 |
| M10x1.25 | 10.0 | 1.25 | 8.8 | 11/32 | 12.0 | 31/64 |
| M12x1.75 | 12.0 | 1.75 | 10.2 | 13/32 | 14.0 | 35/64 |
| M12x1.25 | 12.0 | 1.25 | 10.8 | 27/64 | 14.0 | 35/64 |
| M14x2 | 14.0 | 2.00 | 12.0 | 15/32 | 16.0 | 5/8 |
| M14x1.5 | 14.0 | 1.5 | 12.5 | 1/2 | 16.0 | 5/8 |
| M16x2 | 16.0 | 2.00 | 14.0 | 35/64 | 18.0 | 45/64 |
| M16x1.5 | 16.0 | 1.50 | 14.5 | 37/64 | 18.0 | 45/64 |
| M18x2.5 | 18.0 | 2.50 | 15.5 | 39/64 | 20.0 | 51/64 |
| M18x1.5 | 18.0 | 1.50 | 16.5 | 21/32 | 20.0 | 51/64 |
| M20x2.5 | 20.0 | 2.50 | 17.5 | 11/16 | 22.0 | 7/8 |
| M20x1.5 | 20.0 | 1.50 | 18.5 | 47/64 | 22.0 | 7/8 |
| M22x2.5 | 22.0 | 2.50 | 19.5 | 49/64 | 25.0 | 1 |
| M22x1.5 | 22.0 | 1.50 | 20.5 | 13/16 | 25.0 | 1 |
| M24x3 | 24.0 | 3.00 | 21.0 | 53/64 | 27.0 | 1-5/64 |
| M24x2 | 24.0 | 2.00 | 22.0 | 7/8 | 27.0 | 1-5/64 |
| M27x3 | 27.0 | 3.00 | 24.0 | 15/16 | 30.0 | 1-3/16 |
| M27x2 | 27.0 | 2.0 | 25.0 | 1 | 30.0 | 1-3/16 |
