When designing drilled holes it is best practice to try to match standard drill sizes. The reference chart below helps understand what is considered a standard drill bit, starting from smallest to largest. Holes outside of this range may require specialized tooling. Depending on hole size, the feature may be pocket-milled with an endmill versus drilling.
Sizes on imperial drill kits are typically referenced by numbers or letters. Metric drill let's typically just used the actual measurement. The four-column chart below is a handy cross-reference for drill bit sizes.
Dirll Bit Size Reference Chart |
|---|
0.0059" - 0.1015" | | 0.1024" - 0.2913" | | 0.2950" - 0.9843" | | 0.9844" - 2.0000" |
Size | Decimal Equivalent (in) | | Size | Decimal Equivalent (in) | | Size | Decimal Equivalent (in) | | Size | Decimal Equivalent (in) |
97 | 0.0059 | | 2.60 mm | 0.1024 | | M | 0.295 | | 63/64" | 0.9844 |
96 | 0.0063 | | 37 | 0.104 | | 7.50 mm | 0.2953 | | 1" | 1 |
95 | 0.0067 | | 2.70 mm | 0.1063 | | 19/64" | 0.2969 | | 25.50 mm | 1.0039 |
94 | 0.0071 | | 36 | 0.1065 | | 7.60 mm | 0.2992 | | 1-1/64" | 1.0156 |
93 | 0.0075 | | 2.75 mm | 0.1083 | | N | 0.302 | | 26.00 mm | 1.0236 |
92 | 0.0079 | | 7/64" | 0.1094 | | 7.70 mm | 0.3031 | | 1-1/32" | 1.0312 |
91 | 0.0083 | | 35 | 0.11 | | 7.75 mm | 0.3051 | | 26.50 mm | 1.0433 |
90 | 0.0087 | | 2.80 mm | 0.1102 | | 7.80 mm | 0.3071 | | 1-3/64" | 1.0469 |
89 | 0.0091 | | 34 | 0.111 | | 7.90 mm | 0.311 | | 1-1/16" | 1.0625 |
88 | 0.0095 | | 33 | 0.113 | | 5/16" | 0.3125 | | 27.00 mm | 1.063 |
.25 mm | 0.0098 | | 2.90 mm | 0.1142 | | 8.00 mm | 0.315 | | 1-5/64" | 1.0781 |
87 | 0.01 | | 32 | 0.116 | | O | 0.316 | | 27.50 mm | 1.0827 |
86 | 0.0105 | | 3.00 mm | 0.1181 | | 8.10 mm | 0.3189 | | 1-3/32" | 1.0938 |
85 | 0.011 | | 31 | 0.12 | | 8.20 mm | 0.3228 | | 28.00 mm | 1.1024 |
84 | 0.0115 | | 3.10 mm | 0.122 | | P | 0.323 | | 1-7/64" | 1.1094 |
.30 mm | 0.0118 | | 1/8" | 0.125 | | 8.25 mm | 0.3248 | | 28.50 mm | 1.122 |
83 | 0.012 | | 3.20 mm | 0.126 | | 8.30 mm | 0.3268 | | 1-1/8" | 1.125 |
82 | 0.0125 | | 3.25 mm | 0.128 | | 21/64" | 0.3281 | | 1-9/64" | 1.1406 |
.32 mm | 0.0126 | | 30 | 0.1285 | | 8.40 mm | 0.3307 | | 29.00 mm | 1.1417 |
81 | 0.013 | | 3.30 mm | 0.1299 | | Q | 0.332 | | 1-5/32" | 1.1562 |
80 | 0.0135 | | 3.40 mm | 0.1339 | | 8.50 mm | 0.3346 | | 29.50 mm | 1.1614 |
.35 mm | 0.0138 | | 29 | 0.136 | | 8.60 mm | 0.3386 | | 1-11/64" | 1.1719 |
.36 mm | 0.0142 | | 3.50 mm | 0.1378 | | R | 0.339 | | 30.00 mm | 1.1811 |
79 | 0.0145 | | 28 | 0.1405 | | 8.70 mm | 0.3425 | | 1-3/16" | 1.1875 |
.38 mm | 0.015 | | 9/64" | 0.1406 | | 11/32" | 0.3438 | | 30.50 mm | 1.2008 |
1/64" | 0.0156 | | 3.60 mm | 0.1417 | | 8.75 mm | 0.3445 | | 1-13/64" | 1.2031 |
.40 mm | 0.0157 | | 27 | 0.144 | | 8.80 mm | 0.3465 | | 1-7/32" | 1.2188 |
78 | 0.016 | | 3.70 mm | 0.1457 | | S | 0.348 | | 31.00 mm | 1.2205 |
.42 mm | 0.0165 | | 26 | 0.147 | | 8.90 mm | 0.3504 | | 1-15/64" | 1.2344 |
.44 mm | 0.0173 | | 3.75 mm | 0.1476 | | 9.00 mm | 0.3543 | | 31.50 mm | 1.2402 |
.45 mm | 0.0177 | | 25 | 0.1495 | | T | 0.358 | | 1-1/4" | 1.25 |
77 | 0.018 | | 3.80 mm | 0.1496 | | 9.10 mm | 0.3583 | | 32.00 mm | 1.2598 |
.46 mm | 0.0181 | | 24 | 0.152 | | 23/64" | 0.3594 | | 1-17/64" | 1.2656 |
.48 mm | 0.0189 | | 3.90 mm | 0.1535 | | 9.20 mm | 0.3622 | | 32.50 mm | 1.2795 |
.50 mm | 0.0197 | | 23 | 0.154 | | 9.25 mm | 0.3642 | | 1-9/32" | 1.2812 |
76 | 0.02 | | 5/32" | 0.1562 | | 9.30 mm | 0.3661 | | 1-19/64" | 1.2969 |
75 | 0.021 | | 22 | 0.157 | | U | 0.368 | | 33.00 mm | 1.2992 |
.55 mm | 0.0217 | | 4.00 mm | 0.1575 | | 9.40 mm | 0.3701 | | 1-5/16" | 1.3125 |
74 | 0.0225 | | 21 | 0.159 | | 9.50 mm | 0.374 | | 33.50 mm | 1.3189 |
.60 mm | 0.0236 | | 20 | 0.161 | | 3/8" | 0.375 | | 1-21/64" | 1.3281 |
73 | 0.024 | | 4.10 mm | 0.1614 | | V | 0.377 | | 34.00 mm | 1.3386 |
72 | 0.025 | | 4.20 mm | 0.1654 | | 9.60 mm | 0.378 | | 1-11/32" | 1.3438 |
.65 mm | 0.0256 | | 19 | 0.166 | | 9.70 mm | 0.3819 | | 34.50 mm | 1.3583 |
71 | 0.026 | | 4.25 mm | 0.1673 | | 9.75 mm | 0.3839 | | 1-23/64" | 1.3594 |
.70 mm | 0.0276 | | 4.30 mm | 0.1693 | | 9.80 mm | 0.3858 | | 1-3/8" | 1.375 |
70 | 0.028 | | 18 | 0.1695 | | W | 0.386 | | 35.00 mm | 1.378 |
69 | 0.0292 | | 11/64" | 0.1719 | | 9.90 mm | 0.3898 | | 1-25/64" | 1.3906 |
.75 mm | 0.0295 | | 17 | 0.173 | | 25/64" | 0.3906 | | 35.50 mm | 1.3976 |
68 | 0.031 | | 4.40 mm | 0.1732 | | 10.00 mm | 0.3937 | | 1-13/32" | 1.4062 |
1/32" | 0.0312 | | 16 | 0.177 | | X | 0.397 | | 36.00 mm | 1.4173 |
.80 mm | 0.0315 | | 4.50 mm | 0.1772 | | Y | 0.404 | | 1-27/64" | 1.4219 |
67 | 0.032 | | 15 | 0.18 | | 13/32" | 0.4062 | | 36.50 mm | 1.437 |
66 | 0.033 | | 4.60 mm | 0.1811 | | Z | 0.413 | | 1-7/16" | 1.4375 |
.85 mm | 0.0335 | | 14 | 0.182 | | 10.50 mm | 0.4134 | | 1-29/64" | 1.4531 |
65 | 0.035 | | 13 | 0.185 | | 27/64" | 0.4219 | | 37.00 mm | 1.4567 |
.90 mm | 0.0354 | | 4.70 mm | 0.185 | | 11.00 mm | 0.4331 | | 1-15/32" | 1.4688 |
64 | 0.036 | | 4.75 mm | 0.187 | | 7/16" | 0.4375 | | 37.50 mm | 1.4764 |
63 | 0.037 | | 3/16" | 0.1875 | | 11.50 mm | 0.4528 | | 1-31/64" | 1.4844 |
.95 mm | 0.0374 | | 4.80 mm | 0.189 | | 29/64" | 0.4531 | | 38.00 mm | 1.4961 |
62 | 0.038 | | 12 | 0.189 | | 15/32" | 0.4688 | | 1-1/2" | 1.5 |
61 | 0.039 | | 11 | 0.191 | | 12.00 mm | 0.4724 | | 1-33/64" | 1.5156 |
1.00 mm | 0.0394 | | 4.90 mm | 0.1929 | | 31/64" | 0.4844 | | 38.50 mm | 1.5157 |
60 | 0.04 | | 10 | 0.1935 | | 12.50 mm | 0.4921 | | 1-17/32" | 1.5312 |
59 | 0.041 | | 9 | 0.196 | | 1/2" | 0.5 | | 39.00 mm | 1.5354 |
1.05 mm | 0.0413 | | 5.00 mm | 0.1969 | | 13.00 mm | 0.5118 | | 1-35/64" | 1.5469 |
58 | 0.042 | | 8 | 0.199 | | 33/64" | 0.5156 | | 39.50 mm | 1.5551 |
57 | 0.043 | | 5.10 mm | 0.2008 | | 17/32" | 0.5312 | | 1-9/16" | 1.5625 |
1.10 mm | 0.0433 | | 7 | 0.201 | | 13.50 mm | 0.5315 | | 40.00 mm | 1.5748 |
1.15 mm | 0.0453 | | 13/64" | 0.2031 | | 35/64" | 0.5469 | | 1-37/64" | 1.5781 |
56 | 0.0465 | | 6 | 0.204 | | 14.00 mm | 0.5512 | | 1-19/32" | 1.5938 |
3/64" | 0.0469 | | 5.20 mm | 0.2047 | | 9/16" | 0.5625 | | 40.50 mm | 1.5945 |
1.20 mm | 0.0472 | | 5 | 0.2055 | | 14.50 mm | 0.5709 | | 1-39/64" | 1.6094 |
1.25 mm | 0.0492 | | 5.25 mm | 0.2067 | | 37/64" | 0.5781 | | 41.00 mm | 1.6142 |
1.30 mm | 0.0512 | | 5.30 mm | 0.2087 | | 15.00 mm | 0.5906 | | 1-5/8" | 1.625 |
55 | 0.052 | | 4 | 0.209 | | 19/32" | 0.5938 | | 41.50 mm | 1.6339 |
1.35 mm | 0.0531 | | 5.40 mm | 0.2126 | | 39/64" | 0.6094 | | 1-41/64" | 1.6406 |
54 | 0.055 | | 3 | 0.213 | | 15.50 mm | 0.6102 | | 42.00 mm | 1.6535 |
1.40 mm | 0.0551 | | 5.50 mm | 0.2165 | | 5/8" | 0.625 | | 1-21/32" | 1.6562 |
1.45 mm | 0.0571 | | 7/32" | 0.2188 | | 16.00 mm | 0.6299 | | 1-43/64" | 1.6719 |
1.50 mm | 0.0591 | | 5.60 mm | 0.2205 | | 41/64" | 0.6406 | | 42.50 mm | 1.6732 |
53 | 0.0595 | | 2 | 0.221 | | 16.50 mm | 0.6496 | | 1-11/16" | 1.6875 |
1.55 mm | 0.061 | | 5.70 mm | 0.2244 | | 21/32" | 0.6562 | | 43.00 mm | 1.6929 |
1/16" | 0.0625 | | 5.75 mm | 0.2264 | | 17.00 mm | 0.6693 | | 1-45/64" | 1.7031 |
1.60 mm | 0.063 | | 1 | 0.228 | | 43/64" | 0.6719 | | 43.50 mm | 1.7126 |
52 | 0.0635 | | 5.80 mm | 0.2283 | | 11/16" | 0.6875 | | 1-23/32" | 1.7188 |
1.65 mm | 0.065 | | 5.90 mm | 0.2323 | | 17.50 mm | 0.689 | | 44.00 mm | 1.7323 |
1.70 mm | 0.0669 | | A | 0.234 | | 45/64" | 0.7031 | | 1-47/64" | 1.7344 |
51 | 0.067 | | 15/64" | 0.2344 | | 18.00 mm | 0.7087 | | 1-3/4" | 1.75 |
1.75 mm | 0.0689 | | 6.00 mm | 0.2362 | | 23/32" | 0.7188 | | 44.50 mm | 1.752 |
50 | 0.07 | | B | 0.238 | | 18.50 mm | 0.7283 | | 1-49/64" | 1.7656 |
1.80 mm | 0.0709 | | 6.10 mm | 0.2402 | | 47/64" | 0.7344 | | 45.00 mm | 1.7717 |
1.85 mm | 0.0728 | | C | 0.242 | | 19.00 mm | 0.748 | | 1-25/32" | 1.7812 |
49 | 0.073 | | 6.20 mm | 0.2441 | | 3/4" | 0.75 | | 45.50 mm | 1.7913 |
1.90 mm | 0.0748 | | D | 0.246 | | 49/64" | 0.7656 | | 1-51/64" | 1.7969 |
48 | 0.076 | | 6.25 mm | 0.2461 | | 19.50 mm | 0.7677 | | 46.00 mm | 1.811 |
1.95 mm | 0.0768 | | 6.30 mm | 0.248 | | 25/32" | 0.7812 | | 1-13/16" | 1.8125 |
5/64" | 0.0781 | | 1/4" E | 0.25 | | 20.00 mm | 0.7874 | | 1-53/64" | 1.8281 |
47 | 0.0785 | | 6.40 mm | 0.252 | | 51/64" | 0.7969 | | 46.50 mm | 1.8307 |
2.00 mm | 0.0787 | | 6.50 mm | 0.2559 | | 20.50 mm | 0.8071 | | 1-27/32" | 1.8438 |
2.05 mm | 0.0807 | | F | 0.257 | | 13/16" | 0.8125 | | 47.00 mm | 1.8504 |
46 | 0.081 | | 6.60 mm | 0.2598 | | 21.00 mm | 0.8268 | | 1-55/64" | 1.8594 |
45 | 0.082 | | G | 0.261 | | 53/64" | 0.8281 | | 47.50 mm | 1.8701 |
2.10 mm | 0.0827 | | 6.70 mm | 0.2638 | | 27/32" | 0.8438 | | 1-7/8" | 1.875 |
2.15 mm | 0.0846 | | 17/64" | 0.2656 | | 21.50 mm | 0.8465 | | 48.00 mm | 1.8898 |
44 | 0.086 | | 6.75 mm | 0.2657 | | 55/64" | 0.8594 | | 1-57/64" | 1.8906 |
2.20 mm | 0.0866 | | H | 0.266 | | 22.00 mm | 0.8661 | | 1-29/32" | 1.9062 |
2.25 mm | 0.0886 | | 6.80 mm | 0.2677 | | 7/8" | 0.875 | | 48.50 mm | 1.9094 |
43 | 0.089 | | 6.90 mm | 0.2717 | | 22.50 mm | 0.8858 | | 1-59/64" | 1.9219 |
2.30 mm | 0.0906 | | I | 0.272 | | 57/64" | 0.8906 | | 49.00 mm | 1.9291 |
2.35 mm | 0.0925 | | 7.00 mm | 0.2756 | | 23.00 mm | 0.9055 | | 1-15/16" | 1.9375 |
42 | 0.0935 | | J | 0.277 | | 29/32" | 0.9062 | | 49.50 mm | 1.9488 |
3/32" | 0.0938 | | 7.10 mm | 0.2795 | | 59/64" | 0.9219 | | 1-61/64" | 1.9531 |
2.40 mm | 0.0945 | | K | 0.281 | | 23.50 mm | 0.9252 | | 50.00 mm | 1.9685 |
41 | 0.096 | | 9/32" | 0.2812 | | 15/16" | 0.9375 | | 1-31/32" | 1.9688 |
2.45 mm | 0.0965 | | 7.20 mm | 0.2835 | | 24.00 mm | 0.9449 | | 1-63/64" | 1.9844 |
40 | 0.098 | | 7.25 mm | 0.2854 | | 61/64" | 0.9531 | | 50.50 mm | 1.9882 |
2.50 mm | 0.0984 | | 7.30 mm | 0.2874 | | 24.50 mm | 0.9646 | | 2" | 2 |
39 | 0.0995 | | L | 0.29 | | 31/32" | 0.9688 | | | |
38 | 0.1015 | | 7.40 mm | 0.2913 | | 25.00 mm | 0.9843 | | | |
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