Drill Bit Size Chart (Metric-Imperial Equivalents)

For your convenience, we’ve compiled a simplified chart of drill bit sizes.
drill bit size chart

We trust that the information below is self-explanatory and straightforward.

Gauge Sizing Metric / SI Imperial / US
Number / Letter Size Millimeters Fractional Inches Fractional Inches (Reduced) Decimal Inches
--- 0.010 --- --- 0.0004
104 0.080 --- --- 0.0031
103 0.090 --- --- 0.0035
102 --- --- --- 0.0039
--- 0.100 --- --- 0.0039
101 0.110 --- --- 0.0043
100 0.120 --- --- 0.0047
99 0.130 --- --- 0.0051
98 0.140 --- --- 0.0055
97 0.150 --- --- 0.0059
96 0.160 --- --- 0.0063
95 0.170 --- --- 0.0067
94 0.180 --- --- 0.0071
93 0.190 --- --- 0.0075
--- 0.198 1/128 --- 0.0078
92 0.201 --- --- 0.0079
91 0.210 --- --- 0.0083
90 0.220 --- --- 0.0087
89 0.230 --- --- 0.0091
88 0.240 --- --- 0.0095
--- 0.250 --- --- 0.0098
87 0.254 --- --- 0.0100
--- 0.260 --- --- 0.0102
86 0.270 --- --- 0.0105
85 0.280 --- --- 0.0110
84 0.290 --- --- 0.0115
--- 0.300 --- --- 0.0118
83 0.305 --- --- 0.0120
82 0.318 --- --- 0.0125
81 0.330 --- --- 0.0130
80 0.343 --- --- 0.0135
79 0.368 --- --- 0.0145
--- 0.397 1/64 --- 0.0156
78 0.406 --- --- 0.0160
77 0.457 --- --- 0.0180
--- 0.500 --- --- 0.0197
76 0.508 --- --- 0.0200
75 0.533 --- --- 0.0210
74 0.572 --- --- 0.0225
73 0.610 --- --- 0.0240
72 0.635 --- --- 0.0250
71 0.660 --- --- 0.0260
70 0.710 --- --- 0.0280

69		 0.742 --- --- 0.0292
--- 0.750 --- --- 0.0295
68 0.787 --- --- 0.0310
--- 0.794 2/64 1/32 0.0312
67 0.813 --- --- 0.0320
66 0.838 --- --- 0.0330
65 0.889 --- --- 0.0350
64 0.914 --- --- 0.0360
63 0.940 --- --- 0.0370
62 0.965 --- --- 0.0380
61 0.991 --- --- 0.0390
--- 1.000 --- --- 0.0394
60 1.016 --- --- 0.0400
59 1.041 --- --- 0.0410
58 1.067 --- --- 0.0420
57 1.092 --- --- 0.0430
56 1.181 --- --- 0.0465
--- 1.191 3/64 --- 0.0469
--- 1.250 --- --- 0.0492
55 1.321 --- --- 0.0520
54 1.397 --- --- 0.0550
--- 1.500 --- --- 0.0591
53 1.511 --- --- 0.0595
--- 1.588 4/64   1/16 0.0625
52 1.613 --- --- 0.0635
51 1.702 --- --- 0.0670
--- 1.750 --- --- 0.0689
50 1.778 --- --- 0.0700
--- 1.800 --- --- 0.0709
--- 1.850 --- --- 0.0728
49 1.854 --- --- 0.0730
48 1.930 --- --- 0.0760
--- 1.984   5/64 --- 0.0781
47 1.994 --- --- 0.0785
--- 2.000 --- --- 0.0787
46 2.057 --- --- 0.0810
45 2.083 --- --- 0.0820
44 2.184 --- --- 0.0860
--- 2.250 --- --- 0.0886
43 2.261 --- --- 0.0890
42 2.375 --- --- 0.0935
--- 2.381 6/64   3/32 0.0938
41 2.438 --- --- 0.0960
--- 2.450 --- --- 0.0965
40 2.489 --- --- 0.0980
--- 2.500 --- --- 0.0984
39 2.527 --- --- 0.0995
38 2.578 --- --- 0.1015
37 2.642 --- --- 0.1040
36 2.705 --- --- 0.1065
--- 2.750 --- --- 0.1083
--- 2.778   7/64 --- 0.1094
35 2.794 --- --- 0.1100
34 2.819 --- --- 0.1110
33 2.870 --- --- 0.1130
32 2.946 --- --- 0.1160
--- 3.000 --- --- 0.1181
31 3.048 --- --- 0.1200
--- 3.175 8/64   1/8  0.1250
--- 3.250 --- --- 0.1280
30 3.264 --- --- 0.1285
29 3.454 --- --- 0.1360
--- 3.500 --- --- 0.1378
28 3.569 --- --- 0.1405
--- 3.572   9/64 --- 0.1406
27 3.658 --- --- 0.1440
26 3.734 --- --- 0.1470
--- 3.750 --- --- 0.1476
25 3.797 --- --- 0.1495
24 3.861 --- --- 0.1520
23 3.912 --- --- 0.1540
--- 3.969 10/64   5/32 0.1562
22 3.988 --- --- 0.1570
--- 4.000 --- --- 0.1575
21 4.039 --- --- 0.1590
20 4.089 --- --- 0.1610
19 4.216 --- --- 0.1660
--- 4.250 --- --- 0.1673
18 4.305 --- --- 0.1695
--- 4.366 11/64 --- 0.1720
17 4.394 --- --- 0.1730
16 4.496 --- --- 0.1770
--- 4.500 --- --- 0.1772
15 4.572 --- --- 0.1800
14 4.623 --- --- 0.1820
13 4.469 --- --- 0.1850
--- 4.750 --- --- 0.1870
--- 4.763 12/64   3/16 0.1875
12 4.800 --- --- 0.1890
11 4.850 --- --- 0.1910
10 4.915 --- --- 0.1935
9 4.978 --- --- 0.1960
--- 5.000 --- --- 0.1969
8 5.055 --- --- 0.1990
7 5.105 --- --- 0.2010
--- 5.159 13/64 --- 0.2031
6 5.182 --- --- 0.2040
5 5.220 --- --- 0.2055
--- 5.250 --- --- 0.2067
4 5.309 --- --- 0.2090
3 5.410 --- --- 0.2130
--- 5.500 --- --- 0.2165
---   14/64   7/32 0.2188
2 5.613 --- --- 0.2210
--- 5.750 --- --- 0.2264
1 5.791 --- --- 0.2280
A 5.944 --- --- 0.2340
--- 5.953 15/64 --- 0.2344
--- 6.000 --- --- 0.2362
B 6.045 --- --- 0.2380
--- 6.100 --- --- 0.2402
C 6.147 --- --- 0.2420
--- 6.200 --- --- 0.2441
D 6.248 --- --- 0.2460
--- 6.250 --- --- 0.2461
E 6.350 16/64   1/4  0.2500
--- 6.500 --- --- 0.2559
F 6.528 --- --- 0.2570
--- 6.600 --- --- 0.2598
G 6.629 --- --- 0.2610
--- 6.747 17/64 --- 0.2656
--- 6.750 --- --- 0.2657
H 6.756 --- --- 0.2660
--- 6.800 --- --- 0.2677
I 6.909 --- --- 0.2720
--- 7.000 --- --- 0.2756
J 7.036 --- --- 0.2770
--- 7.100 --- --- 0.2795
K 7.137 --- --- 0.2810
--- 7.144 18/64   9/32 0.2813
--- 7.250 --- --- 0.2854
--- 7.300 --- --- 0.2874
L 7.366 --- --- 0.2900
--- 7.400 --- --- 0.2913
M  7.493 --- --- 0.2950
--- 7.500 --- --- 0.2953
--- 7.541 19/64 --- 0.2969
--- 7.600 --- --- 0.2992
N 7.671 --- --- 0.3020
--- 7.750 --- --- 0.3051
--- 7.938 20/64   5/16 0.3125
--- 8.000 --- --- 0.3150
O 8.026 --- --- 0.3160
--- 8.100 --- --- 0.3189
--- 8.200 --- --- 0.3228
P 8.204 --- --- 0.3230
--- 8.250 --- --- 0.3248
--- 8.300 --- --- 0.3268
--- 8.334 21/64 --- 0.3281
Q 8.433 --- --- 0.3320
--- 8.500 --- --- 0.3346
R 8.611 --- --- 0.3390
--- 8.700 --- --- 0.3425
--- 8.731 22/64 11/32 0.3438
--- 8.750 --- --- 0.3445
S 8.839 --- --- 0.3480
--- 9.000 --- --- 0.3543
T 9.093 --- --- 0.3580
--- 9.128 23/64 --- 0.3594
--- 9.250 --- --- 0.3642
U 9.347 --- --- 0.3680
--- 9.500 --- --- 0.3740
--- 9.525 24/64   3/8  0.3750
V 9.576 --- --- 0.3770
--- 9.600 --- --- 0.3780
--- 9.700 --- --- 0.3819
--- 9.750 --- --- 0.3839
--- 9.800 --- --- 0.3858
W 9.804 --- --- 0.3860
--- 9.922 25/64 --- 0.3906
--- 10.000 --- --- 0.3937
X 10.080 --- --- 0.3970
--- 10.084 --- --- 0.4016
Y 10.260 --- --- 0.4040
--- 10.490 26/64 13/32 0.4063
Z 10.490 --- --- 0.4130
--- 10.500 --- --- 0.4134
--- 10.716 27/64 --- 0.4219
--- 11.000 --- --- 0.4331
--- 11.112 28/64   7/16 0.4375
--- 11.500 --- --- 0.4528
--- 11.509 29/64 --- 0.4531
--- 11.906 30/64 15/32 0.4688
--- 12.000 --- --- 0.4724
--- 12.200 --- --- 0.4803
--- 12.303 31/64 --- 0.4844
--- 12.500 --- --- 0.4921
--- 12.700 32/64   1/2  0.5000
--- 12.800 --- --- 0.5039
--- 13.000 --- --- 0.5118
--- 13.097 33/64 --- 0.5156
--- 13.494 34/64 17/32 0.5312
--- 13.500 --- --- 0.5315
--- 13.891 35/64 --- 0.5469
--- 14.000 --- --- 0.5512
--- 14.288 36/64   9/16 0.5625
--- 14.500 --- --- 0.5709
--- 14.684 37/64 --- 0.5781
--- 15.000 --- --- 0.5906
--- 15.081 38/64 19/32 0.5938
--- 15.478 39/64 --- 0.6094
--- 15.500 --- --- 0.6102
--- 15.875 40/64   5/8  0.6250
--- 16.000 --- --- 0.6299
--- 16.272 41/64 --- 0.6406
--- 16.500 --- --- 0.6496
--- 16.669 42/64 21/32 0.6563
--- 17.000 --- --- 0.6693
--- 17.066 43/64 --- 0.6719
--- 17.462 44/64 11/16 0.6875
--- 17.500 --- --- 0.6890
--- 17.859 45/64 --- 0.7031
--- 18.000 --- --- 0.7087
--- 18.256 46/64 23/32 0.7188
--- 18.500 --- --- 0.7283
--- 18.653 47/64 --- 0.7344
--- 19.000 --- --- 0.7480
--- 19.050 48/64   3/4  0.7500
--- 19.447 49/64 --- 0.7656
--- 19.500 --- --- 0.7677
--- 19.844 50/64 25/32 0.7813
--- 20.000 --- --- 0.7874
--- 20.241  51/64 --- 0.7969
--- 20.500 --- --- 0.8071
--- 20.638 52/64 13/16 0.8125
--- 21.000 --- --- 0.8268
--- 21.034 53/64 --- 0.8281
--- 21.431 54/64 27/32 0.8438
--- 21.500 --- --- 0.8465
--- 21.828 55/64 --- 0.8594
--- 22.000 --- --- 0.8661
--- 22.225 56/64   7/8  0.8750
--- 22.500 --- --- 0.8858
--- 22.622 57/64 --- 0.8906
--- 23.000 --- --- 0.9055
--- 23.019 58/64 29/32 0.9062
--- 23.416 59/64 --- 0.9219
--- 23.500 --- --- 0.9252
--- 23.812 60/64 15/16 0.9375
--- 24.000 --- --- 0.9449
--- 24.209 61/64 --- 0.9531
--- 24.500 --- --- 0.9646
--- 24.606 62/64 31/32 0.9688
--- 25.000 --- --- 0.9843
--- 25.003 63/64 --- 0.9844
--- 25.400 64/64 1       1.0000

Table values compiled from: 

Notes: 

  • Not all metric drill bits have imperial equivalents, and vice versa. 
  • Some metric values are close enough to essentially have the same imperial counterpart. 
  • Some values are rounded to their nearest thousandth millimeters and ten-thousandth decimal inches.

 

AIMS' Note on Safe Use of Hand Tools

  • Inspection: Before using any tool, carefully inspect it for cracks, chips, loose handles, worn / mushroomed heads or any other signs of damage. Damaged or defective tools may cause harm! Ensure all guards are in place.
  • Right tool for the job: Make sure you understand the intended purpose of each tool and choose the correct one for your specific job. Don't try to make a screwdriver work as a pry bar or a wrench as a hammer.
  • Safe handling: Carry sharp tools pointed down and away from your body. Never carry tools in your pockets where they can cause injury. When passing a tool to someone, extend the handle first.
  • PPE: Wear safety glasses or goggles to protect your eyes from flying debris. Consider gloves depending on the tool and task to prevent cuts or blisters but without compromising comfort, dexterity and protection. If working with noisy tools, wear ear protection.
  • Maintenance: Keep your tools clean, sharp and properly maintained. Store them in a safe and organised place when not in use.

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