All four series in one list, sorted smallest to largest: number drills #80 to #1, letter drills A to Z, fractional drills from 1/64" to 1" in 1/64" steps, and standard metric drills from 1.0 to 13.0 mm including the common metric tap drill sizes (3.3, 4.2, 6.8, 8.5, 10.2 mm). Read down the left half first, then the right. Two sizes per row.[1]
| Drill | Decimal (in) | mm | Drill | Decimal (in) | mm |
|---|---|---|---|---|---|
| #80 | 0.0135 | 0.34 | #4 | 0.2090 | 5.31 |
| #79 | 0.0145 | 0.37 | #3 | 0.2130 | 5.41 |
| 1/64" | 0.0156 | 0.40 | 5.5 mm | 0.2165 | 5.50 |
| #78 | 0.0160 | 0.41 | 7/32" | 0.2188 | 5.56 |
| #77 | 0.0180 | 0.46 | #2 | 0.2210 | 5.61 |
| #76 | 0.0200 | 0.51 | #1 | 0.2280 | 5.79 |
| #75 | 0.0210 | 0.53 | A | 0.2340 | 5.94 |
| #74 | 0.0225 | 0.57 | 15/64" | 0.2344 | 5.95 |
| #73 | 0.0240 | 0.61 | 6 mm | 0.2362 | 6.00 |
| #72 | 0.0250 | 0.64 | B | 0.2380 | 6.05 |
| #71 | 0.0260 | 0.66 | C | 0.2420 | 6.15 |
| #70 | 0.0280 | 0.71 | D | 0.2460 | 6.25 |
| #69 | 0.0292 | 0.74 | E | 0.2500 | 6.35 |
| #68 | 0.0310 | 0.79 | 1/4" | 0.2500 | 6.35 |
| 1/32" | 0.0312 | 0.79 | 6.5 mm | 0.2559 | 6.50 |
| #67 | 0.0320 | 0.81 | F | 0.2570 | 6.53 |
| #66 | 0.0330 | 0.84 | G | 0.2610 | 6.63 |
| #65 | 0.0350 | 0.89 | 17/64" | 0.2656 | 6.75 |
| #64 | 0.0360 | 0.91 | H | 0.2660 | 6.76 |
| #63 | 0.0370 | 0.94 | 6.8 mm | 0.2677 | 6.80 |
| #62 | 0.0380 | 0.97 | I | 0.2720 | 6.91 |
| #61 | 0.0390 | 0.99 | 7 mm | 0.2756 | 7.00 |
| 1 mm | 0.0394 | 1.00 | J | 0.2770 | 7.04 |
| #60 | 0.0400 | 1.02 | K | 0.2810 | 7.14 |
| #59 | 0.0410 | 1.04 | 9/32" | 0.2812 | 7.14 |
| #58 | 0.0420 | 1.07 | L | 0.2900 | 7.37 |
| #57 | 0.0430 | 1.09 | M | 0.2950 | 7.49 |
| #56 | 0.0465 | 1.18 | 7.5 mm | 0.2953 | 7.50 |
| 3/64" | 0.0469 | 1.19 | 19/64" | 0.2969 | 7.54 |
| #55 | 0.0520 | 1.32 | N | 0.3020 | 7.67 |
| #54 | 0.0550 | 1.40 | 5/16" | 0.3125 | 7.94 |
| 1.5 mm | 0.0591 | 1.50 | 8 mm | 0.3150 | 8.00 |
| #53 | 0.0595 | 1.51 | O | 0.3160 | 8.03 |
| 1/16" | 0.0625 | 1.59 | P | 0.3230 | 8.20 |
| #52 | 0.0635 | 1.61 | 21/64" | 0.3281 | 8.33 |
| #51 | 0.0670 | 1.70 | Q | 0.3320 | 8.43 |
| #50 | 0.0700 | 1.78 | 8.5 mm | 0.3346 | 8.50 |
| #49 | 0.0730 | 1.85 | R | 0.3390 | 8.61 |
| #48 | 0.0760 | 1.93 | 11/32" | 0.3438 | 8.73 |
| 5/64" | 0.0781 | 1.98 | S | 0.3480 | 8.84 |
| #47 | 0.0785 | 1.99 | 9 mm | 0.3543 | 9.00 |
| 2 mm | 0.0787 | 2.00 | T | 0.3580 | 9.09 |
| #46 | 0.0810 | 2.06 | 23/64" | 0.3594 | 9.13 |
| #45 | 0.0820 | 2.08 | U | 0.3680 | 9.35 |
| #44 | 0.0860 | 2.18 | 9.5 mm | 0.3740 | 9.50 |
| #43 | 0.0890 | 2.26 | 3/8" | 0.3750 | 9.53 |
| #42 | 0.0935 | 2.37 | V | 0.3770 | 9.58 |
| 3/32" | 0.0938 | 2.38 | W | 0.3860 | 9.80 |
| #41 | 0.0960 | 2.44 | 25/64" | 0.3906 | 9.92 |
| #40 | 0.0980 | 2.49 | 10 mm | 0.3937 | 10.00 |
| 2.5 mm | 0.0984 | 2.50 | X | 0.3970 | 10.08 |
| #39 | 0.0995 | 2.53 | 10.2 mm | 0.4016 | 10.20 |
| #38 | 0.1015 | 2.58 | Y | 0.4040 | 10.26 |
| #37 | 0.1040 | 2.64 | 13/32" | 0.4062 | 10.32 |
| #36 | 0.1065 | 2.71 | Z | 0.4130 | 10.49 |
| 7/64" | 0.1094 | 2.78 | 10.5 mm | 0.4134 | 10.50 |
| #35 | 0.1100 | 2.79 | 27/64" | 0.4219 | 10.72 |
| #34 | 0.1110 | 2.82 | 11 mm | 0.4331 | 11.00 |
| #33 | 0.1130 | 2.87 | 7/16" | 0.4375 | 11.11 |
| #32 | 0.1160 | 2.95 | 11.5 mm | 0.4528 | 11.50 |
| 3 mm | 0.1181 | 3.00 | 29/64" | 0.4531 | 11.51 |
| #31 | 0.1200 | 3.05 | 15/32" | 0.4688 | 11.91 |
| 1/8" | 0.1250 | 3.18 | 12 mm | 0.4724 | 12.00 |
| #30 | 0.1285 | 3.26 | 31/64" | 0.4844 | 12.30 |
| 3.3 mm | 0.1299 | 3.30 | 12.5 mm | 0.4921 | 12.50 |
| #29 | 0.1360 | 3.45 | 1/2" | 0.5000 | 12.70 |
| 3.5 mm | 0.1378 | 3.50 | 13 mm | 0.5118 | 13.00 |
| #28 | 0.1405 | 3.57 | 33/64" | 0.5156 | 13.10 |
| 9/64" | 0.1406 | 3.57 | 17/32" | 0.5312 | 13.49 |
| #27 | 0.1440 | 3.66 | 35/64" | 0.5469 | 13.89 |
| #26 | 0.1470 | 3.73 | 9/16" | 0.5625 | 14.29 |
| #25 | 0.1495 | 3.80 | 37/64" | 0.5781 | 14.68 |
| #24 | 0.1520 | 3.86 | 19/32" | 0.5938 | 15.08 |
| #23 | 0.1540 | 3.91 | 39/64" | 0.6094 | 15.48 |
| 5/32" | 0.1562 | 3.97 | 5/8" | 0.6250 | 15.88 |
| #22 | 0.1570 | 3.99 | 41/64" | 0.6406 | 16.27 |
| 4 mm | 0.1575 | 4.00 | 21/32" | 0.6562 | 16.67 |
| #21 | 0.1590 | 4.04 | 43/64" | 0.6719 | 17.07 |
| #20 | 0.1610 | 4.09 | 11/16" | 0.6875 | 17.46 |
| 4.2 mm | 0.1654 | 4.20 | 45/64" | 0.7031 | 17.86 |
| #19 | 0.1660 | 4.22 | 23/32" | 0.7188 | 18.26 |
| #18 | 0.1695 | 4.31 | 47/64" | 0.7344 | 18.65 |
| 11/64" | 0.1719 | 4.37 | 3/4" | 0.7500 | 19.05 |
| #17 | 0.1730 | 4.39 | 49/64" | 0.7656 | 19.45 |
| #16 | 0.1770 | 4.50 | 25/32" | 0.7812 | 19.84 |
| 4.5 mm | 0.1772 | 4.50 | 51/64" | 0.7969 | 20.24 |
| #15 | 0.1800 | 4.57 | 13/16" | 0.8125 | 20.64 |
| #14 | 0.1820 | 4.62 | 53/64" | 0.8281 | 21.03 |
| #13 | 0.1850 | 4.70 | 27/32" | 0.8438 | 21.43 |
| 3/16" | 0.1875 | 4.76 | 55/64" | 0.8594 | 21.83 |
| #12 | 0.1890 | 4.80 | 7/8" | 0.8750 | 22.23 |
| #11 | 0.1910 | 4.85 | 57/64" | 0.8906 | 22.62 |
| #10 | 0.1935 | 4.91 | 29/32" | 0.9062 | 23.02 |
| #9 | 0.1960 | 4.98 | 59/64" | 0.9219 | 23.42 |
| 5 mm | 0.1969 | 5.00 | 15/16" | 0.9375 | 23.81 |
| #8 | 0.1990 | 5.05 | 61/64" | 0.9531 | 24.21 |
| #7 | 0.2010 | 5.11 | 31/32" | 0.9688 | 24.61 |
| 13/64" | 0.2031 | 5.16 | 63/64" | 0.9844 | 25.00 |
| #6 | 0.2040 | 5.18 | 1" | 1.0000 | 25.40 |
| #5 | 0.2055 | 5.22 |
Reading a callout. A drawing that says "DRILL #7 (.201)" or ".201 DIA" means the same hole. Modern drawings increasingly give the decimal only and let the shop choose the tool; this chart is the translation table in both directions.
Drilled-hole accuracy. A twist drill is a roughing tool. Expect a drilled hole to run 0.002 to 0.005" oversize in most materials, with more variation in deep holes. For a hole with a real diameter tolerance, plan on drilling undersize and reaming or boring to finish, and see our DFM guide for how hole callouts drive cost.
Metric substitution. Because the list is sorted by size, near-equivalents sit next to each other: 6.8 mm (0.2677") lands under two thousandths over the letter H (0.2660"), and 3.3 mm (0.1299") falls between #30 and #29. Shops running mixed inch and metric work use these crossovers daily.
A shop without a full metric drill index can still tap metric threads from the inch drawers. The table gives the closest number, letter or fractional drill to each metric coarse tap drill, how far off it is, and the percent of thread it actually produces (the metric drill's own percent first, the inch substitute's second). Anything between about 65% and 80% is normal shop practice; the substitutes that push past 80% are the ones to watch, because more thread means more tapping torque and a higher chance of a broken tap.
| Metric Tap | Tap Drill (mm) | Tap Dec. (in) | Nearest Inch Drill | Inch Dec. (in) | Diff. (in) | Thread: mm → inch drill |
|---|---|---|---|---|---|---|
| M2 × 0.4 | 1.60 mm | 0.0630 | 1/16" | 0.0625 | −0.0005 | 77% → 79% |
| M2.5 × 0.45 | 2.05 mm | 0.0807 | #46 | 0.0810 | +0.0003 | 77% → 76% |
| M3 × 0.5 | 2.50 mm | 0.0984 | #40 | 0.0980 | −0.0004 | 77% → 79% |
| M4 × 0.7 | 3.30 mm | 0.1299 | #30 | 0.1285 | −0.0014 | 77% → 81% |
| M5 × 0.8 | 4.20 mm | 0.1654 | #19 | 0.1660 | +0.0006 | 77% → 75% |
| M6 × 1.0 | 5.00 mm | 0.1969 | #9 | 0.1960 | −0.0009 | 77% → 79% |
| M8 × 1.25 | 6.80 mm | 0.2677 | H | 0.2660 | −0.0017 | 74% → 77% |
| M10 × 1.5 | 8.50 mm | 0.3346 | Q | 0.3320 | −0.0026 | 77% → 80% |
| M12 × 1.75 | 10.20 mm | 0.4016 | Y | 0.4040 | +0.0024 | 79% → 76% |
| M16 × 2.0 | 14.00 mm | 0.5512 | 35/64" | 0.5469 | −0.0043 | 77% → 81% |
| M20 × 2.5 | 17.50 mm | 0.6890 | 11/16" | 0.6875 | −0.0015 | 77% → 78% |
From #80 micro-holes to bored diameters with tenths tolerances, we drill, ream, bore, and inspect to print with AS9100D traceability.