Drill Bit Sizes
Drill bits can be purchased in a variety of sizes; fractions of an inch, millimeters (mm), gauge (numbers & letters. Table 1 provides a conversion of the different sizes of drill bits from fractions of an inch to millimeters (mm) and gauge numbers and letters.

Figure 1 - Set of drill bits
The drill bit sizes shown are those that are readily available to purchase. Other sizes, especially in millimeter sizes, may be available on special order. It should be noted that all drill bit styles may not be available in every size.
Selection of drill bits
.
| Table 1 - Drill Bit Sizes - Decimal, Fractions, Millimeters, Numbers & Letters |
Decimal/ Inch |
Drill Bits Available |
Fraction/ Inch |
Millimeters (mm) |
Numbers/ Letters |
0.0063 |
|
0.16 |
|
0.0067 |
|
0.17 |
|
0.0071 |
|
0.18 |
|
0.0075 |
|
0.19 |
|
0.0079 |
|
0.20 |
|
0.0083 |
|
0.21 |
|
0.0087 |
|
0.22 |
|
0.0091 |
|
0.23 |
|
0.0094 |
|
0.24 |
|
0.0098 |
|
0.25 |
|
0.0102 |
|
0.26 |
|
0.0106 |
|
0.27 |
|
0.0110 |
|
0.28 |
|
0.0114 |
|
0.29 |
|
0.0118 |
|
0.30 |
|
0.0126 |
|
0.32 |
|
0.0134 |
|
0.34 |
|
0.0135 |
|
|
80 |
0.0138 |
|
0.35 |
|
0.0142 |
|
0.36 |
|
0.0145 |
|
|
79 |
0.0150 |
|
0.38 |
|
0.0156 |
1/64 |
|
|
0.0157 |
|
0.40 |
|
0.0160 |
|
|
78 |
0.0165 |
|
0.42 |
|
0.0173 |
|
0.44 |
|
0.0177 |
|
0.45 |
|
0.0180 |
|
|
77 |
0.0181 |
|
0.46 |
|
0.1890 |
|
0.48 |
|
0.1970 |
|
0.50 |
|
0.0200 |
|
|
76 |
0.0210 |
|
|
75 |
0.0217 |
|
0.55 |
|
0.0225 |
|
|
74 |
0.0236 |
|
0.60 |
|
0.0240 |
|
|
73 |
0.0250 |
|
|
72 |
0.0256 |
|
0.65 |
|
0.0260 |
|
|
71 |
0.0276 |
|
0.70 |
|
0.0280 |
|
|
70 |
0.0292 |
|
|
69 |
0.0295 |
|
0.75 |
|
0.0310 |
|
|
68 |
0.0313 |
1/32 |
|
|
0.0315 |
|
0.80 |
|
0.0320 |
|
|
67 |
0.0330 |
|
|
66 |
0.0335 |
|
0.85 |
|
0.0350 |
|
|
65 |
0.0354 |
|
0.90 |
|
0.0360 |
|
|
64 |
0.0370 |
|
|
63 |
0.3740 |
|
0.95 |
|
0.0380 |
|
|
62 |
0.0390 |
|
|
61 |
0.0394 |
|
1.00 |
|
0.0400 |
|
|
60 |
0.0410 |
|
|
59 |
0.0430 |
|
1.05 |
|
0.0420 |
|
|
58 |
0.0430 |
|
|
57 |
0.0433 |
|
1.10 |
|
0.0453 |
|
1.15 |
|
0.0465 |
|
|
56 |
0.0469 |
3/64 |
|
|
0.0473 |
|
1.20 |
|
0.0492 |
|
1.25 |
|
0.0512 |
|
1.30 |
|
0.0520 |
|
|
55 |
0.0531 |
|
1.35 |
|
0.0550 |
|
|
54 |
0.0551 |
|
1.40 |
|
0.0571 |
|
1.45 |
|
0.0591 |
|
1.50 |
|
0.0595 |
|
|
53 |
0.0610 |
|
1.55 |
|
0.0625 |
1/16 |
|
|
0.0630 |
|
1.60 |
|
0.0635 |
|
|
52 |
0.0650 |
|
1.65 |
|
0.0690 |
|
1.70 |
|
0.0670 |
|
|
51 |
0.0689 |
|
1.75 |
|
0.0700 |
|
|
50 |
0.0709 |
|
1.80 |
|
0.0728 |
|
1.85 |
|
0.0730 |
|
|
49 |
0.0748 |
|
1.90 |
|
0.0760 |
|
|
48 |
0.0768 |
|
1.95 |
|
0.0781 |
5/64 |
|
|
0.0785 |
|
|
47 |
0.0787 |
|
2.00 |
|
0.0807 |
|
2.05 |
|
0.0810 |
|
|
46 |
0.0820 |
|
|
45 |
0.0827 |
|
2.10 |
|
0.0846 |
|
2.15 |
|
0.0860 |
|
|
44 |
0.0866 |
|
2.20 |
|
0.0886 |
|
2.25 |
|
0.0890 |
|
|
43 |
0.0906 |
|
2.30 |
|
0.0925 |
|
2.35 |
|
0.0935 |
|
|
42 |
0.0938 |
3/32 |
|
|
0.0945 |
|
2.40 |
|
0.0960 |
|
|
41 |
0.0965 |
|
2.45 |
|
0.0980 |
|
|
40 |
0.0984 |
|
2.50 |
|
0.0995 |
|
|
39 |
0.1015 |
|
|
38 |
0.1024 |
|
2.60 |
|
0.1040 |
|
|
37 |
0.1063 |
|
2.70 |
|
0.1065 |
|
|
36 |
0.1083 |
|
2.75 |
|
0.1094 |
7/64 |
|
|
0.1100 |
|
|
35 |
0.1102 |
|
2.80 |
|
0.1110 |
|
|
34 |
0.1130 |
|
|
33 |
0.1142 |
|
2.90 |
|
0.1160 |
|
|
32 |
0.1181 |
|
3.00 |
|
0.1200 |
|
|
31 |
0.1220 |
|
3.10 |
|
0.1250 |
1/8 |
|
|
0.1260 |
|
3.20 |
|
0.1280 |
|
3.25 |
|
0.1285 |
|
|
30 |
0.1299 |
|
3.30 |
|
0.1339 |
|
3.40 |
|
0.1360 |
|
|
29 |
0.1378 |
|
3.50 |
|
0.1405 |
|
|
28 |
0.1406 |
9/64 |
|
|
0.1417 |
|
3.60 |
|
0.1440 |
|
|
27 |
0.1457 |
|
3.70 |
|
0.1470 |
|
|
26 |
0.1476 |
|
3.75 |
|
0.1495 |
|
|
25 |
0.14.96 |
|
3.80 |
|
0.1520 |
|
|
24 |
0.1535 |
|
3.90 |
|
0.1540 |
|
|
23 |
|
|
Decimal/
Inch |
Drill Bits Available |
Fraction/
Inch |
Millimeters |
Numbers/
Letters |
0.1563 |
5/32 |
|
|
0.1570 |
|
|
22 |
0.1575 |
|
4.00 |
|
0.1590 |
|
|
21 |
0.1610 |
|
|
20 |
0.1614 |
|
4.10 |
|
0.1654 |
|
4.20 |
|
0.1660 |
|
|
19 |
0.1673 |
|
4.25 |
|
0.1693 |
|
4.30 |
|
0.1695 |
|
|
18 |
0.1719 |
11/64 |
|
|
0.1730 |
|
|
17 |
0.1732 |
|
4.40 |
|
0.1770 |
|
|
16 |
0.1772 |
|
4.50 |
|
0.1800 |
|
|
15 |
0.1811 |
|
4.60 |
|
0.1820 |
|
|
14 |
0.1850 |
|
4.70 |
13 |
0.1870 |
|
4.75 |
|
0.1875 |
3/16 |
|
|
0.1890 |
|
4.80 |
12 |
0.1910 |
|
|
11 |
0.1929 |
|
4.90 |
|
0.1935 |
|
|
10 |
0.1960 |
|
|
9 |
0.1969 |
|
5.00 |
|
0.1990 |
|
|
8 |
0.2008 |
|
5.10 |
|
0.2010 |
|
|
7 |
0.2031 |
13/64 |
|
|
0.2040 |
|
|
6 |
0.2047 |
|
5.20 |
|
0.2055 |
|
|
5 |
0.2067 |
|
5.25 |
|
0.2087 |
|
5.30 |
|
0.2090 |
|
|
4 |
0.2026 |
|
5.40 |
|
0.2130 |
|
|
3 |
0.2165 |
|
5.50 |
|
0.2188 |
7/32 |
|
|
0.2205 |
|
5.60 |
|
0.2210 |
|
|
2 |
0.2244 |
|
5.70 |
|
0.2264 |
|
5.75 |
|
0.2280 |
|
|
1 |
0.2283 |
|
5.80 |
|
0.2323 |
|
5.90 |
|
0.2340 |
|
|
A |
0.2344 |
15/64 |
|
|
0.2362 |
|
6.00 |
|
0.2380 |
|
|
B |
0.2402 |
|
6.10 |
|
0.2420 |
|
|
C |
0.2441 |
|
6.20 |
|
0.2460 |
|
|
D |
0.2461 |
|
6.25 |
|
0.2480 |
|
6.30 |
|
0.2500 |
1/4 |
|
E |
0.2520 |
|
6.40 |
|
0.2529 |
|
6.50 |
|
0.2570 |
|
|
F |
0.2598 |
|
6.60 |
|
0.2610 |
|
|
G |
0.2638 |
|
6.70 |
|
0.2656 |
17/64 |
|
|
0.2657 |
|
6.75 |
|
0.2660 |
|
|
H |
0.2677 |
|
6.80 |
|
0.2717 |
|
6.90 |
|
0.2720 |
|
|
I |
0.2756 |
|
7.00 |
|
0.2770 |
|
|
J |
0.2795 |
|
7.10 |
|
0.2810 |
|
|
K |
0.2813 |
9/32 |
|
|
0.2835 |
|
7.20 |
|
0.2854 |
|
7.25 |
|
0.2874 |
|
7.30 |
|
0.2900 |
|
|
L |
0.2913 |
|
7.40 |
|
0.2950 |
|
|
M |
0.2953 |
|
7.50 |
|
0.2969 |
19/64 |
|
|
0.2992 |
|
7.60 |
|
0.3020 |
|
|
N |
0.3031 |
|
7.70 |
|
0.3051 |
|
7.75 |
|
0.3071 |
|
7.80 |
|
0.3110 |
|
7.90 |
|
0.3125 |
5/16 |
|
|
0.3150 |
|
8.00 |
|
0.3160 |
|
|
O |
0.3189 |
|
8.10 |
|
0.3228 |
|
8.20 |
|
0.3230 |
|
|
P |
0.3248 |
|
8.25 |
|
0.3268 |
|
8.30 |
|
0.3281 |
21/64 |
|
|
0.3307 |
|
8.40 |
|
0.3320 |
|
|
Q |
0.3346 |
|
8.50 |
|
0.3386 |
|
8.60 |
|
0.3390 |
|
|
R |
0.3425 |
|
8.70 |
|
0.3438 |
11/32 |
|
|
0.3445 |
|
8.75 |
|
0.3465 |
|
8.80 |
|
0.3480 |
|
|
S |
0.3504 |
|
8.90 |
|
0.3543 |
|
9.00 |
|
0.3580 |
|
|
T |
0.3583 |
|
9.10 |
|
0.3594 |
23/64 |
|
|
0.3622 |
|
9.20 |
|
0.3642 |
|
9.25 |
|
0.3661 |
|
9.30 |
|
0.3680 |
|
|
U |
0.3701 |
|
9.40 |
|
0.3740 |
|
9.50 |
|
0.3750 |
3/8 |
|
|
0.3770 |
|
|
V |
0.3780 |
|
9.60 |
|
0.3819 |
|
9.70 |
|
0.3838 |
|
9.75 |
|
0.3858 |
|
9.80 |
|
0.3860 |
|
|
W |
0.3898 |
|
9.90 |
|
0.3906 |
25/64 |
|
|
0.3937 |
|
10.00 |
|
0.3970 |
|
|
X |
0.4016 |
|
10.20 |
|
0.4040 |
|
|
Y |
0.4063 |
13/32 |
|
|
0.4130 |
|
|
Z |
0.4138 |
|
10.50 |
|
0.4219 |
27/64 |
|
|
0.4252 |
|
10.80 |
|
0.4330 |
|
11.00 |
|
0.4375 |
7/16 |
|
|
0.4409 |
|
11.20 |
|
0.4528 |
|
11.50 |
|
0.4531 |
29/64 |
|
|
0.4646 |
|
11.80 |
|
0.4688 |
15/32 |
|
|
0.4724 |
|
12.00 |
|
0.4803 |
|
12.20 |
|
0.4844 |
31/64 |
|
|
0.4921 |
|
12.50 |
|
0.5000 |
1/2 |
|
|
|