Drill Bit Size Chart
Every US drill bit size in one place: fractional, number, and letter drills, each with its exact decimal inch and millimeter diameter. Type a measurement into the finder to get the closest bits, or print the combined chart for the shop wall.
Find the closest drill bit
Unit
- 1/4" Fractional0.2500 in · 6.350 mm · exact
- E Letter0.2500 in · 6.350 mm · exact
- D Letter0.2460 in · 6.248 mm · −0.0040 in
- F Letter0.2570 in · 6.528 mm · +0.0070 in
- C Letter0.2420 in · 6.147 mm · −0.0080 in
All drill sizes, smallest to largest
Fractional, number, and letter bits merged into one list from 1/64 in to 1 in, so you can see which sizes fall between each other.
| Drill | Type | Decimal inch | Millimeters |
|---|---|---|---|
| #80 | number | 0.0135 | 0.343 |
| #79 | number | 0.0145 | 0.368 |
| 1/64" | fraction | 0.0156 | 0.397 |
| #78 | number | 0.0160 | 0.406 |
| #77 | number | 0.0180 | 0.457 |
| #76 | number | 0.0200 | 0.508 |
| #75 | number | 0.0210 | 0.533 |
| #74 | number | 0.0225 | 0.571 |
| #73 | number | 0.0240 | 0.610 |
| #72 | number | 0.0250 | 0.635 |
| #71 | number | 0.0260 | 0.660 |
| #70 | number | 0.0280 | 0.711 |
| #69 | number | 0.0292 | 0.742 |
| #68 | number | 0.0310 | 0.787 |
| 1/32" | fraction | 0.0313 | 0.794 |
| #67 | number | 0.0320 | 0.813 |
| #66 | number | 0.0330 | 0.838 |
| #65 | number | 0.0350 | 0.889 |
| #64 | number | 0.0360 | 0.914 |
| #63 | number | 0.0370 | 0.940 |
| #62 | number | 0.0380 | 0.965 |
| #61 | number | 0.0390 | 0.991 |
| #60 | number | 0.0400 | 1.016 |
| #59 | number | 0.0410 | 1.041 |
| #58 | number | 0.0420 | 1.067 |
| #57 | number | 0.0430 | 1.092 |
| #56 | number | 0.0465 | 1.181 |
| 3/64" | fraction | 0.0469 | 1.191 |
| #55 | number | 0.0520 | 1.321 |
| #54 | number | 0.0550 | 1.397 |
| #53 | number | 0.0595 | 1.511 |
| 1/16" | fraction | 0.0625 | 1.587 |
| #52 | number | 0.0635 | 1.613 |
| #51 | number | 0.0670 | 1.702 |
| #50 | number | 0.0700 | 1.778 |
| #49 | number | 0.0730 | 1.854 |
| #48 | number | 0.0760 | 1.930 |
| 5/64" | fraction | 0.0781 | 1.984 |
| #47 | number | 0.0785 | 1.994 |
| #46 | number | 0.0810 | 2.057 |
| #45 | number | 0.0820 | 2.083 |
| #44 | number | 0.0860 | 2.184 |
| #43 | number | 0.0890 | 2.261 |
| #42 | number | 0.0935 | 2.375 |
| 3/32" | fraction | 0.0938 | 2.381 |
| #41 | number | 0.0960 | 2.438 |
| #40 | number | 0.0980 | 2.489 |
| #39 | number | 0.0995 | 2.527 |
| #38 | number | 0.1015 | 2.578 |
| #37 | number | 0.1040 | 2.642 |
| #36 | number | 0.1065 | 2.705 |
| 7/64" | fraction | 0.1094 | 2.778 |
| #35 | number | 0.1100 | 2.794 |
| #34 | number | 0.1110 | 2.819 |
| #33 | number | 0.1130 | 2.870 |
| #32 | number | 0.1160 | 2.946 |
| #31 | number | 0.1200 | 3.048 |
| 1/8" | fraction | 0.1250 | 3.175 |
| #30 | number | 0.1285 | 3.264 |
| #29 | number | 0.1360 | 3.454 |
| #28 | number | 0.1405 | 3.569 |
| 9/64" | fraction | 0.1406 | 3.572 |
| #27 | number | 0.1440 | 3.658 |
| #26 | number | 0.1470 | 3.734 |
| #25 | number | 0.1495 | 3.797 |
| #24 | number | 0.1520 | 3.861 |
| #23 | number | 0.1540 | 3.912 |
| 5/32" | fraction | 0.1563 | 3.969 |
| #22 | number | 0.1570 | 3.988 |
| #21 | number | 0.1590 | 4.039 |
| #20 | number | 0.1610 | 4.089 |
| #19 | number | 0.1660 | 4.216 |
| #18 | number | 0.1695 | 4.305 |
| 11/64" | fraction | 0.1719 | 4.366 |
| #17 | number | 0.1730 | 4.394 |
| #16 | number | 0.1770 | 4.496 |
| #15 | number | 0.1800 | 4.572 |
| #14 | number | 0.1820 | 4.623 |
| #13 | number | 0.1850 | 4.699 |
| 3/16" | fraction | 0.1875 | 4.762 |
| #12 | number | 0.1890 | 4.801 |
| #11 | number | 0.1910 | 4.851 |
| #10 | number | 0.1935 | 4.915 |
| #9 | number | 0.1960 | 4.978 |
| #8 | number | 0.1990 | 5.055 |
| #7 | number | 0.2010 | 5.105 |
| 13/64" | fraction | 0.2031 | 5.159 |
| #6 | number | 0.2040 | 5.182 |
| #5 | number | 0.2055 | 5.220 |
| #4 | number | 0.2090 | 5.309 |
| #3 | number | 0.2130 | 5.410 |
| 7/32" | fraction | 0.2188 | 5.556 |
| #2 | number | 0.2210 | 5.613 |
| #1 | number | 0.2280 | 5.791 |
| A | letter | 0.2340 | 5.944 |
| 15/64" | fraction | 0.2344 | 5.953 |
| B | letter | 0.2380 | 6.045 |
| C | letter | 0.2420 | 6.147 |
| D | letter | 0.2460 | 6.248 |
| 1/4" | fraction | 0.2500 | 6.350 |
| E | letter | 0.2500 | 6.350 |
| F | letter | 0.2570 | 6.528 |
| G | letter | 0.2610 | 6.629 |
| 17/64" | fraction | 0.2656 | 6.747 |
| H | letter | 0.2660 | 6.756 |
| I | letter | 0.2720 | 6.909 |
| J | letter | 0.2770 | 7.036 |
| K | letter | 0.2810 | 7.137 |
| 9/32" | fraction | 0.2813 | 7.144 |
| L | letter | 0.2900 | 7.366 |
| M | letter | 0.2950 | 7.493 |
| 19/64" | fraction | 0.2969 | 7.541 |
| N | letter | 0.3020 | 7.671 |
| 5/16" | fraction | 0.3125 | 7.938 |
| O | letter | 0.3160 | 8.026 |
| P | letter | 0.3230 | 8.204 |
| 21/64" | fraction | 0.3281 | 8.334 |
| Q | letter | 0.3320 | 8.433 |
| R | letter | 0.3390 | 8.611 |
| 11/32" | fraction | 0.3438 | 8.731 |
| S | letter | 0.3480 | 8.839 |
| T | letter | 0.3580 | 9.093 |
| 23/64" | fraction | 0.3594 | 9.128 |
| U | letter | 0.3680 | 9.347 |
| 3/8" | fraction | 0.3750 | 9.525 |
| V | letter | 0.3770 | 9.576 |
| W | letter | 0.3860 | 9.804 |
| 25/64" | fraction | 0.3906 | 9.922 |
| X | letter | 0.3970 | 10.084 |
| Y | letter | 0.4040 | 10.262 |
| 13/32" | fraction | 0.4063 | 10.319 |
| Z | letter | 0.4130 | 10.490 |
| 27/64" | fraction | 0.4219 | 10.716 |
| 7/16" | fraction | 0.4375 | 11.112 |
| 29/64" | fraction | 0.4531 | 11.509 |
| 15/32" | fraction | 0.4688 | 11.906 |
| 31/64" | fraction | 0.4844 | 12.303 |
| 1/2" | fraction | 0.5000 | 12.700 |
| 33/64" | fraction | 0.5156 | 13.097 |
| 17/32" | fraction | 0.5313 | 13.494 |
| 35/64" | fraction | 0.5469 | 13.891 |
| 9/16" | fraction | 0.5625 | 14.287 |
| 37/64" | fraction | 0.5781 | 14.684 |
| 19/32" | fraction | 0.5938 | 15.081 |
| 39/64" | fraction | 0.6094 | 15.478 |
| 5/8" | fraction | 0.6250 | 15.875 |
| 41/64" | fraction | 0.6406 | 16.272 |
| 21/32" | fraction | 0.6563 | 16.669 |
| 43/64" | fraction | 0.6719 | 17.066 |
| 11/16" | fraction | 0.6875 | 17.462 |
| 45/64" | fraction | 0.7031 | 17.859 |
| 23/32" | fraction | 0.7188 | 18.256 |
| 47/64" | fraction | 0.7344 | 18.653 |
| 3/4" | fraction | 0.7500 | 19.050 |
| 49/64" | fraction | 0.7656 | 19.447 |
| 25/32" | fraction | 0.7813 | 19.844 |
| 51/64" | fraction | 0.7969 | 20.241 |
| 13/16" | fraction | 0.8125 | 20.637 |
| 53/64" | fraction | 0.8281 | 21.034 |
| 27/32" | fraction | 0.8438 | 21.431 |
| 55/64" | fraction | 0.8594 | 21.828 |
| 7/8" | fraction | 0.8750 | 22.225 |
| 57/64" | fraction | 0.8906 | 22.622 |
| 29/32" | fraction | 0.9063 | 23.019 |
| 59/64" | fraction | 0.9219 | 23.416 |
| 15/16" | fraction | 0.9375 | 23.813 |
| 61/64" | fraction | 0.9531 | 24.209 |
| 31/32" | fraction | 0.9688 | 24.606 |
| 63/64" | fraction | 0.9844 | 25.003 |
| 1" | fraction | 1.0000 | 25.400 |
Charts by drill series
Fractional drill sizes
| Size | Inch | mm |
|---|---|---|
| 1/64" | 0.0156 | 0.397 |
| 1/32" | 0.0313 | 0.794 |
| 3/64" | 0.0469 | 1.191 |
| 1/16" | 0.0625 | 1.587 |
| 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 | 4.762 |
| 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 | 11.112 |
| 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 | 14.287 |
| 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 | 17.462 |
| 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 | 20.637 |
| 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 |
Number drill sizes (#1–#80)
| Size | Inch | mm |
|---|---|---|
| #1 | 0.2280 | 5.791 |
| #2 | 0.2210 | 5.613 |
| #3 | 0.2130 | 5.410 |
| #4 | 0.2090 | 5.309 |
| #5 | 0.2055 | 5.220 |
| #6 | 0.2040 | 5.182 |
| #7 | 0.2010 | 5.105 |
| #8 | 0.1990 | 5.055 |
| #9 | 0.1960 | 4.978 |
| #10 | 0.1935 | 4.915 |
| #11 | 0.1910 | 4.851 |
| #12 | 0.1890 | 4.801 |
| #13 | 0.1850 | 4.699 |
| #14 | 0.1820 | 4.623 |
| #15 | 0.1800 | 4.572 |
| #16 | 0.1770 | 4.496 |
| #17 | 0.1730 | 4.394 |
| #18 | 0.1695 | 4.305 |
| #19 | 0.1660 | 4.216 |
| #20 | 0.1610 | 4.089 |
| #21 | 0.1590 | 4.039 |
| #22 | 0.1570 | 3.988 |
| #23 | 0.1540 | 3.912 |
| #24 | 0.1520 | 3.861 |
| #25 | 0.1495 | 3.797 |
| #26 | 0.1470 | 3.734 |
| #27 | 0.1440 | 3.658 |
| #28 | 0.1405 | 3.569 |
| #29 | 0.1360 | 3.454 |
| #30 | 0.1285 | 3.264 |
| #31 | 0.1200 | 3.048 |
| #32 | 0.1160 | 2.946 |
| #33 | 0.1130 | 2.870 |
| #34 | 0.1110 | 2.819 |
| #35 | 0.1100 | 2.794 |
| #36 | 0.1065 | 2.705 |
| #37 | 0.1040 | 2.642 |
| #38 | 0.1015 | 2.578 |
| #39 | 0.0995 | 2.527 |
| #40 | 0.0980 | 2.489 |
| #41 | 0.0960 | 2.438 |
| #42 | 0.0935 | 2.375 |
| #43 | 0.0890 | 2.261 |
| #44 | 0.0860 | 2.184 |
| #45 | 0.0820 | 2.083 |
| #46 | 0.0810 | 2.057 |
| #47 | 0.0785 | 1.994 |
| #48 | 0.0760 | 1.930 |
| #49 | 0.0730 | 1.854 |
| #50 | 0.0700 | 1.778 |
| #51 | 0.0670 | 1.702 |
| #52 | 0.0635 | 1.613 |
| #53 | 0.0595 | 1.511 |
| #54 | 0.0550 | 1.397 |
| #55 | 0.0520 | 1.321 |
| #56 | 0.0465 | 1.181 |
| #57 | 0.0430 | 1.092 |
| #58 | 0.0420 | 1.067 |
| #59 | 0.0410 | 1.041 |
| #60 | 0.0400 | 1.016 |
| #61 | 0.0390 | 0.991 |
| #62 | 0.0380 | 0.965 |
| #63 | 0.0370 | 0.940 |
| #64 | 0.0360 | 0.914 |
| #65 | 0.0350 | 0.889 |
| #66 | 0.0330 | 0.838 |
| #67 | 0.0320 | 0.813 |
| #68 | 0.0310 | 0.787 |
| #69 | 0.0292 | 0.742 |
| #70 | 0.0280 | 0.711 |
| #71 | 0.0260 | 0.660 |
| #72 | 0.0250 | 0.635 |
| #73 | 0.0240 | 0.610 |
| #74 | 0.0225 | 0.571 |
| #75 | 0.0210 | 0.533 |
| #76 | 0.0200 | 0.508 |
| #77 | 0.0180 | 0.457 |
| #78 | 0.0160 | 0.406 |
| #79 | 0.0145 | 0.368 |
| #80 | 0.0135 | 0.343 |
Letter drill sizes (A–Z)
| Size | Inch | mm |
|---|---|---|
| A | 0.2340 | 5.944 |
| B | 0.2380 | 6.045 |
| C | 0.2420 | 6.147 |
| D | 0.2460 | 6.248 |
| E | 0.2500 | 6.350 |
| F | 0.2570 | 6.528 |
| G | 0.2610 | 6.629 |
| H | 0.2660 | 6.756 |
| I | 0.2720 | 6.909 |
| J | 0.2770 | 7.036 |
| K | 0.2810 | 7.137 |
| L | 0.2900 | 7.366 |
| M | 0.2950 | 7.493 |
| N | 0.3020 | 7.671 |
| O | 0.3160 | 8.026 |
| P | 0.3230 | 8.204 |
| Q | 0.3320 | 8.433 |
| R | 0.3390 | 8.611 |
| S | 0.3480 | 8.839 |
| T | 0.3580 | 9.093 |
| U | 0.3680 | 9.347 |
| V | 0.3770 | 9.576 |
| W | 0.3860 | 9.804 |
| X | 0.3970 | 10.084 |
| Y | 0.4040 | 10.262 |
| Z | 0.4130 | 10.490 |
How to pick the right drill bit size
- Tapping threads: use the tap drill listed for your thread in the tap drill chart, not the screw's own diameter.
- Clearance holes: go one or two sizes larger than the screw diameter so the bolt slides through.
- Pilot holes in wood: roughly match the screw's root (the solid core between the threads); go slightly larger in hardwood.
- Measuring an unmarked bit: measure across the margins (the outer edges of the flutes) with calipers, not across the shank, then use the finder above.
Drill Bit Size Chart FAQ
What are the standard drill bit sizes?
In the US there are three series. Fractional bits go from 1/64 in to 1 in in 1/64 in steps. Number bits run from #80 (0.0135 in) up to #1 (0.228 in), and letter bits continue from A (0.234 in) to Z (0.413 in). Metric bits are sized directly in millimeters.
Why do number drills get bigger as the number gets smaller?
Number drills come from the old wire gauge system, where a higher number meant thinner wire. So #80 is the smallest and #1 is the largest. Letter sizes then pick up where #1 leaves off, getting larger from A to Z.
What size drill bit is 1/4 inch?
A 1/4 in bit is 0.2500 in, or 6.35 mm. Letter E is also 0.250 in, so the two are interchangeable. The closest metric bit is 6.4 mm.
How do I convert a drill size to millimeters?
Multiply the decimal inch size by 25.4. For example, a #7 drill is 0.201 in × 25.4 = 5.105 mm. The table on this page already shows the millimeter size for every bit.
Sources
Number and letter diameters follow ASME B94.11M as tabulated in Wikipedia's “Drill bit sizes” conversion table. Fractional sizes are exact 64ths of an inch; millimeters are inches × 25.4.