Drill Bit to Wire Gauge Conversion Chart

Use this chart to determine which drill bit size will work with your particular gauge of wire.

Last edited: 11/13/2019
This comprehensive chart will help you determine which drill bit you should use when drilling wire. Includes Brown & Sharpe, millimeter and inch measurements, and the corresponding drill bit size.
B&S mm inches drill size
0 8.26 .325 21/64  
1 7.34 .289 9/32  
2 6.52 .257 1/4  
3 5.81 .229 7/32 1
4 5.18 .204 13/64 6
5 4.62 .182 3/16 15
6 4.11 .162 5/32 20
7 3.66 .144 9/64 27
8 3.25 .128 1/8 30
9 2.90 .114    
10 2.59 .102   38
11 2.31 .091   43
12 2.06 .081 5/64 46
13 1.83 .072   50
14 1.63 .064 1/16 51
15 1.45 .057   52
16 1.30 .051   54
17 1.14 .045 3/64 55
18 1.02 .040   56
19 0.914 .036   60
20 0.812 .032 1/32 65
21 0.711 .028   67
22 0.635 .025   70
23 0.558 .022   71
24 0.508 .020   74
25 0.457 .018   75
26 0.406 .016 1/64 77
27 0.355 .014   78
28 0.304 .012   79
29 0.279 .011   80
30 0.254 .010