American National Standards Institute (ANSI) drill bit sizes are used predominantly in the United States and utilize the Imperial measurement system. Drill bit sizes under ANSI are given in fractions of an inch, typically starting at 1/64 inch, then incrementing in 1/64 inch steps for smaller sizes, and up to larger sizes such as 1/2 inch, 1 inch, and so on. The system also includes a number series (from size 80, the smallest, to size 1) and a letter series (from A to Z), both used for diameters smaller than 1/4 inch. This provides a broad spectrum of drill bit sizes to cater to various applications.
On the other hand, metric drill bit sizes, largely used outside the United States, are based on the International System of Units (SI) measurements. Metric drill bit sizes are typically given in millimeters (mm), incrementing in 0.1mm steps for smaller sizes and in 0.5mm steps for larger sizes. Metric drill bit sizes offer a similarly wide array of sizes for all kinds of applications. As for converting ISO (metric) to inches, a conversion factor of 25.4 is used, as there are 25.4 millimeters in one inch. So, to convert a metric drill bit size to inches, you would divide the size in millimeters by 25.4. For instance, a 10mm drill bit would be approximately 0.394 inches.
You know how vital it is to have the right tool for the job. And when it comes to drilling, precision is the name of the game. So here’s your ultimate drill bit size chart, an essential piece of kit that’s gonna be your go-to resource when dealing with different standards. This bad boy allows you to effortlessly navigate between ANSI, metric, and ISO measurements. Say goodbye to guesswork, whether you’re dealing with fractions of an inch, the trusty millimeter, or need to convert between the two. Remember, size matters and this chart is your roadmap to ensure you’ve always got the right drill bit at hand. It’s not just about power, it’s about precision, and this chart’s got your back. Strap on your tool belt, it’s time to drill with confidence.
Drill Bit Size Chart
ANSI Size Drill Bit Chart | ISO (Metric Size Drills) & Conversion to Inches | |||||||||||
Drill (in.) |
Decimal | Drill (in.) |
Decimal | Drill (in.) |
Decimal | Drill (mm) |
Decimal (in.) |
Drill (mm) |
Decimal (in.) |
Drill (mm) |
Decimal (in.) |
|
80 | .0135 | 1/8 | .1250 | O | .3160 | .35 | .0138 | 3.4 | .1339 | 8.0 | .3150 | |
79 | .0145 | 30 | .1285 | P | .3230 | .4 | .0157 | 3.5 | .1378 | 8.1 | .3189 | |
1/64 | .0156 | 29 | .1360 | 21/64 | .3281 | .45 | .0177 | 3.6 | .1417 | 8.2 | .3228 | |
78 | .0160 | 28 | .1405 | Q | .3320 | .5 | .0197 | 3.7 | .1457 | 8.25 | .3248 | |
77 | .0180 | 9/64 | .1406 | R | .3390 | .55 | .0217 | 3.75 | .1477 | 8.3 | .3267 | |
76 | .0200 | 27 | .1440 | 11/32 | .3437 | .6 | .0236 | 3.8 | .1496 | 8.4 | .3307 | |
75 | .0210 | 26 | .1470 | S | .3480 | .65 | .0256 | 3.9 | .1535 | 8.5 | .3346 | |
74 | .0225 | 25 | .1495 | T | .3580 | .7 | .0276 | 4.0 | .1575 | 8.6 | .3386 | |
73 | .0240 | 24 | .1520 | 23/64 | .3594 | .75 | .0295 | 4.1 | .1614 | 8.7 | .3425 | |
72 | .0250 | 23 | .1540 | U | .3680 | .8 | .0315 | 4.2 | .1654 | 8.75 | .3445 | |
71 | .0260 | 5/32 | .1562 | 3/8 | .3750 | .85 | .0335 | 4.25 | .1674 | 8.8 | .3465 | |
70 | .0280 | 22 | .1570 | V | .3770 | .9 | .0355 | 4.3 | .1693 | 8.9 | .3504 | |
69 | .0292 | 21 | .1590 | W | .3860 | .95 | .0374 | 4.4 | .1732 | 9.0 | .3543 | |
68 | .0310 | 20 | .1610 | 25/64 | .3906 | 1.0 | .0394 | 4.5 | .1771 | 9.1 | .3583 | |
1/32 | .0313 | 19 | .1660 | X | .3970 | 1.05 | .0413 | 4.6 | .1811 | 9.2 | .3622 | |
67 | .0320 | 18 | .1695 | Y | .4040 | 1.1 | .0433 | 4.7 | .1850 | 9.25 | .3642 | |
66 | .0330 | 11/64 | .1719 | 13/32 | .4062 | 1.15 | .0453 | 4.75 | .1870 | 9.35 | .3661 | |
65 | .0350 | 17 | .1730 | Z | .4130 | 1.2 | .0472 | 4.8 | .1890 | 9.4 | .3701 | |
64 | .0360 | 16 | .1770 | 27/64 | .4219 | 1.25 | .0492 | 4.9 | .1929 | 9.5 | .3740 | |
63 | .0370 | 15 | .1800 | 7/16 | .4375 | 1.3 | .0512 | 5.0 | .1968 | 9.6 | .3780 | |
62 | .0380 | 14 | .1820 | 29/64 | .4531 | 1.35 | .0531 | 5.1 | .2008 | 9.7 | .3819 | |
61 | .0390 | 13 | .1850 | 15/32 | .4687 | 1.4 | .0551 | 5.2 | .2047 | 9.75 | .3839 | |
60 | .0400 | 3/16 | .1875 | 31/64 | .4844 | 1.45 | .0571 | 5.25 | .2067 | 9.8 | .3858 | |
59 | .0410 | 12 | .1890 | 1/2 | .5000 | 1.5 | .0591 | 5.3 | .2087 | 9.9 | .3898 | |
58 | .0420 | 11 | .1910 | 33/64 | .5156 | 1.55 | .0610 | 5.4 | .2126 | 10.0 | .3937 | |
57 | .0430 | 10 | .1935 | 17/32 | .5312 | 1.6 | .0629 | 5.5 | .2165 | 10.5 | .4133 | |
56 | .0465 | 9 | .1960 | 35/64 | .5469 | 1.65 | .0650 | 5.6 | .2205 | 11.0 | .4331 | |
3/64 | .0469 | 8 | .1990 | 9/16 | .5625 | 1.7 | .0669 | 5.7 | .2244 | 11.5 | .4528 | |
55 | .0520 | 7 | .2010 | 37/64 | .5781 | 1.75 | .0689 | 5.75 | .2264 | 12.0 | .4724 | |
54 | .0550 | 13/64 | .2031 | 19/32 | .5937 | 1.8 | .0709 | 5.8 | .2283 | 12.5 | .4921 | |
53 | .0595 | 6 | .2040 | 39/64 | .6094 | 1.85 | .0728 | 5.9 | .2323 | 13.0 | .5118 | |
1/16 | .0625 | 5 | .2055 | 5/8 | .6250 | 1.9 | .0748 | 6.0 | .2362 | 13.5 | .5315 | |
52 | .0635 | 4 | .2090 | 41/64 | .6406 | 1.95 | .0768 | 6.1 | .2401 | 14.0 | .5512 | |
51 | .0670 | 3 | .2130 | 21/32 | .6562 | 2.0 | .0787 | 6.2 | .2441 | 14.5 | .5708 | |
50 | .0700 | 7/32 | .2187 | 43/64 | .6719 | 2.05 | .0807 | 6.25 | .2461 | 15.0 | .5906 | |
49 | .0730 | 2 | .2210 | 11/16 | .6875 | 2.1 | .0827 | 6.3 | .2480 | 15.5 | .6102 | |
48 | .0760 | 1 | .2280 | 45/64 | .7031 | 2.15 | .0846 | 6.4 | .2520 | 16.0 | .6300 | |
5/64 | .0781 | A | .2340 | 23/32 | .7187 | 2.2 | .0866 | 6.5 | .2559 | 16.5 | .6496 | |
47 | .0785 | 15/64 | .2344 | 47/64 | .7344 | 2.25 | .0886 | 6.6 | .2598 | 17.0 | .6693 | |
46 | .0810 | B | .2380 | 3/4 | .7500 | 2.3 | .0905 | 6.7 | .2638 | 17.5 | .6889 | |
45 | .0820 | C | .2420 | 49/64 | .7656 | 2.35 | .0925 | 6.75 | .2658 | 18.0 | .7087 | |
44 | .0860 | D | .2460 | 25/32 | .7812 | 2.4 | .0945 | 6.8 | .2677 | 18.5 | .7283 | |
43 | .0890 | E | .2500 | 51/64 | .7969 | 2.45 | .0965 | 6.9 | .2716 | 19.0 | .7480 | |
42 | .0935 | 1/4 | .2500 | 13/16 | .8125 | 2.5 | .0984 | 7.0 | .2756 | 19.5 | .7677 | |
3/32 | .0937 | F | .2570 | 53/64 | .8281 | 2.55 | .1004 | 7.1 | .2795 | 20.0 | .7874 | |
41 | .0960 | G | .2610 | 27/32 | .8437 | 2.6 | .1024 | 7.2 | .2835 | 20.5 | .8071 | |
40 | .0980 | 17/64 | .2656 | 55/64 | .8594 | 2.65 | .1043 | 7.25 | .2855 | 21.0 | .8268 | |
39 | .0995 | H | .2660 | 7/8 | .8750 | 2.7 | .1063 | 7.3 | .2874 | 21.5 | .8465 | |
38 | .1015 | I | .2720 | 57/64 | .8906 | 2.75 | .1083 | 7.4 | .2913 | 22.0 | .8661 | |
37 | .1040 | J | .2770 | 29/32 | .9062 | 2.8 | .1102 | 7.5 | .2953 | 22.5 | .8858 | |
36 | .1065 | K | .2811 | 59/64 | .9219 | 2.9 | .1142 | 7.6 | .2990 | 23.0 | .9055 | |
7/64 | .1093 | 9/32 | .2812 | 15/16 | .9375 | 3.0 | .1181 | 7.7 | .3031 | 23.5 | .9252 | |
35 | .1100 | L | .2900 | 61/64 | .9531 | 3.1 | .1220 | 7.75 | .3051 | 24.0 | .9449 | |
34 | .1110 | M | .2950 | 31/32 | .9687 | 3.2 | .1260 | 7.8 | .3071 | 24.5 | .9646 | |
33 | .1130 | 19/64 | .2968 | 63/64 | .9844 | 3.25 | .1280 | 7.9 | .3110 | 25.0 | .9843 | |
32 | .1160 | N | .3020 | 1 | 1.000 | 3.3 | .1299 | |||||
31 | .1200 | 5/16 | .3125 |