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This drill bit size chart includes three main categorization systems:
- Fractional Sizes – The standard imperial measurements (1/64″, 1/32″, etc.) with their decimal inch and metric (mm) equivalents.
- Letter Sizes – These range from A to Z, with corresponding decimal inch and metric conversions.
- Number Sizes – These range from #1 (largest) to #80 (smallest), commonly used for precision work.
- Metric Sizes – The most common metric drill bit sizes with their decimal inch equivalents.
Fractional Sizes (Standard)
| Fraction (inches) | Decimal (inches) | Metric (mm) |
|---|---|---|
| 1/64 | 0.0156 | 0.397 |
| 1/32 | 0.0313 | 0.794 |
| 3/64 | 0.0469 | 1.191 |
| 1/16 | 0.0625 | 1.588 |
| 5/64 | 0.0781 | 1.984 |
| 3/32 | 0.0938 | 2.381 |
| 7/64 | 0.1094 | 2.778 |
| 1/8 | 0.1250 | 3.175 |
| 9/64 | 0.1406 | 3.572 |
| 5/32 | 0.1563 | 3.969 |
| 11/64 | 0.1719 | 4.366 |
| 3/16 | 0.1875 | 4.763 |
| 13/64 | 0.2031 | 5.159 |
| 7/32 | 0.2188 | 5.556 |
| 15/64 | 0.2344 | 5.953 |
| 1/4 | 0.2500 | 6.350 |
| 17/64 | 0.2656 | 6.747 |
| 9/32 | 0.2813 | 7.144 |
| 19/64 | 0.2969 | 7.541 |
| 5/16 | 0.3125 | 7.938 |
| 21/64 | 0.3281 | 8.334 |
| 11/32 | 0.3438 | 8.731 |
| 23/64 | 0.3594 | 9.128 |
| 3/8 | 0.3750 | 9.525 |
| 25/64 | 0.3906 | 9.922 |
| 13/32 | 0.4063 | 10.319 |
| 27/64 | 0.4219 | 10.716 |
| 7/16 | 0.4375 | 11.113 |
| 29/64 | 0.4531 | 11.509 |
| 15/32 | 0.4688 | 11.906 |
| 31/64 | 0.4844 | 12.303 |
| 1/2 | 0.5000 | 12.700 |
| 33/64 | 0.5156 | 13.097 |
| 17/32 | 0.5313 | 13.494 |
| 35/64 | 0.5469 | 13.891 |
| 9/16 | 0.5625 | 14.288 |
| 37/64 | 0.5781 | 14.684 |
| 19/32 | 0.5938 | 15.081 |
| 39/64 | 0.6094 | 15.478 |
| 5/8 | 0.6250 | 15.875 |
| 41/64 | 0.6406 | 16.272 |
| 21/32 | 0.6563 | 16.669 |
| 43/64 | 0.6719 | 17.066 |
| 11/16 | 0.6875 | 17.463 |
| 45/64 | 0.7031 | 17.859 |
| 23/32 | 0.7188 | 18.256 |
| 47/64 | 0.7344 | 18.653 |
| 3/4 | 0.7500 | 19.050 |
| 49/64 | 0.7656 | 19.447 |
| 25/32 | 0.7813 | 19.844 |
| 51/64 | 0.7969 | 20.241 |
| 13/16 | 0.8125 | 20.638 |
| 53/64 | 0.8281 | 21.034 |
| 27/32 | 0.8438 | 21.431 |
| 55/64 | 0.8594 | 21.828 |
| 7/8 | 0.8750 | 22.225 |
| 57/64 | 0.8906 | 22.622 |
| 29/32 | 0.9063 | 23.019 |
| 59/64 | 0.9219 | 23.416 |
| 15/16 | 0.9375 | 23.813 |
| 61/64 | 0.9531 | 24.209 |
| 31/32 | 0.9688 | 24.606 |
| 63/64 | 0.9844 | 25.003 |
| 1 | 1.0000 | 25.400 |
Letter Sizes
| Letter | Decimal (inches) | Metric (mm) |
|---|---|---|
| A | 0.234 | 5.944 |
| B | 0.238 | 6.045 |
| C | 0.242 | 6.147 |
| D | 0.246 | 6.248 |
| E | 0.250 | 6.350 |
| F | 0.257 | 6.528 |
| G | 0.261 | 6.629 |
| H | 0.266 | 6.756 |
| I | 0.272 | 6.909 |
| J | 0.277 | 7.036 |
| K | 0.281 | 7.137 |
| L | 0.290 | 7.366 |
| M | 0.295 | 7.493 |
| N | 0.302 | 7.671 |
| O | 0.316 | 8.026 |
| P | 0.323 | 8.204 |
| Q | 0.332 | 8.433 |
| R | 0.339 | 8.611 |
| S | 0.348 | 8.839 |
| T | 0.358 | 9.093 |
| U | 0.368 | 9.347 |
| V | 0.377 | 9.576 |
| W | 0.386 | 9.804 |
| X | 0.397 | 10.084 |
| Y | 0.404 | 10.262 |
| Z | 0.413 | 10.490 |
Number Sizes
| Number | Decimal (inches) | Metric (mm) |
|---|---|---|
| 1 | 0.228 | 5.791 |
| 2 | 0.221 | 5.613 |
| 3 | 0.213 | 5.410 |
| 4 | 0.209 | 5.309 |
| 5 | 0.205 | 5.207 |
| 6 | 0.204 | 5.182 |
| 7 | 0.201 | 5.105 |
| 8 | 0.199 | 5.055 |
| 9 | 0.196 | 4.978 |
| 10 | 0.1935 | 4.915 |
| 11 | 0.191 | 4.851 |
| 12 | 0.189 | 4.801 |
| 13 | 0.185 | 4.699 |
| 14 | 0.182 | 4.623 |
| 15 | 0.180 | 4.572 |
| 16 | 0.177 | 4.496 |
| 17 | 0.173 | 4.394 |
| 18 | 0.1695 | 4.305 |
| 19 | 0.166 | 4.216 |
| 20 | 0.161 | 4.089 |
| 21 | 0.159 | 4.039 |
| 22 | 0.157 | 3.988 |
| 23 | 0.154 | 3.912 |
| 24 | 0.152 | 3.861 |
| 25 | 0.1495 | 3.797 |
| 26 | 0.147 | 3.734 |
| 27 | 0.144 | 3.658 |
| 28 | 0.1405 | 3.569 |
| 29 | 0.136 | 3.454 |
| 30 | 0.1285 | 3.264 |
| 31 | 0.120 | 3.048 |
| 32 | 0.116 | 2.946 |
| 33 | 0.113 | 2.870 |
| 34 | 0.111 | 2.819 |
| 35 | 0.110 | 2.794 |
| 36 | 0.1065 | 2.705 |
| 37 | 0.104 | 2.642 |
| 38 | 0.1015 | 2.578 |
| 39 | 0.0995 | 2.527 |
| 40 | 0.098 | 2.489 |
| 41 | 0.096 | 2.438 |
| 42 | 0.0935 | 2.375 |
| 43 | 0.089 | 2.261 |
| 44 | 0.086 | 2.184 |
| 45 | 0.082 | 2.083 |
| 46 | 0.081 | 2.057 |
| 47 | 0.0785 | 1.994 |
| 48 | 0.076 | 1.930 |
| 49 | 0.073 | 1.854 |
| 50 | 0.070 | 1.778 |
| 51 | 0.067 | 1.702 |
| 52 | 0.0635 | 1.613 |
| 53 | 0.0595 | 1.511 |
| 54 | 0.055 | 1.397 |
| 55 | 0.052 | 1.321 |
| 56 | 0.0465 | 1.181 |
| 57 | 0.043 | 1.092 |
| 58 | 0.042 | 1.067 |
| 59 | 0.041 | 1.041 |
| 60 | 0.040 | 1.016 |
| 61 | 0.039 | 0.991 |
| 62 | 0.038 | 0.965 |
| 63 | 0.037 | 0.940 |
| 64 | 0.036 | 0.914 |
| 65 | 0.035 | 0.889 |
| 66 | 0.033 | 0.838 |
| 67 | 0.032 | 0.813 |
| 68 | 0.031 | 0.787 |
| 69 | 0.0292 | 0.742 |
| 70 | 0.028 | 0.711 |
| 71 | 0.026 | 0.660 |
| 72 | 0.025 | 0.635 |
| 73 | 0.024 | 0.610 |
| 74 | 0.0225 | 0.572 |
| 75 | 0.021 | 0.533 |
| 76 | 0.020 | 0.508 |
| 77 | 0.018 | 0.457 |
| 78 | 0.016 | 0.406 |
| 79 | 0.0145 | 0.368 |
| 80 | 0.0135 | 0.343 |
Metric Sizes (Common)
| Metric (mm) | Decimal (inches) |
|---|---|
| 0.5 | 0.0197 |
| 1.0 | 0.0394 |
| 1.5 | 0.0591 |
| 2.0 | 0.0787 |
| 2.5 | 0.0984 |
| 3.0 | 0.1181 |
| 3.5 | 0.1378 |
| 4.0 | 0.1575 |
| 4.5 | 0.1772 |
| 5.0 | 0.1969 |
| 5.5 | 0.2165 |
| 6.0 | 0.2362 |
| 6.5 | 0.2559 |
| 7.0 | 0.2756 |
| 7.5 | 0.2953 |
| 8.0 | 0.3150 |
| 8.5 | 0.3346 |
| 9.0 | 0.3543 |
| 9.5 | 0.3740 |
| 10.0 | 0.3937 |
| 10.5 | 0.4134 |
| 11.0 | 0.4331 |
| 11.5 | 0.4528 |
| 12.0 | 0.4724 |
| 12.5 | 0.4921 |
| 13.0 | 0.5118 |
| 13.5 | 0.5315 |
| 14.0 | 0.5512 |
| 14.5 | 0.5709 |
| 15.0 | 0.5906 |
| 15.5 | 0.6102 |
| 16.0 | 0.6299 |
| 16.5 | 0.6496 |
| 17.0 | 0.6693 |
| 17.5 | 0.6890 |
| 18.0 | 0.7087 |
| 18.5 | 0.7283 |
| 19.0 | 0.7480 |
| 19.5 | 0.7677 |
| 20.0 | 0.7874 |
Find a large array of Drill Bits at MISUMI USA, and find more charts and articles at MISUMI’s Mech Lab Blog including a screw threads size chart.
Author: Scott Bredemann | Updated: 03/31/2025
Disclaimer
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers’ or manufacturers’ deliverables within MISUMI’s network. Buyers are responsible for specifying their part requirements
