Drill Bit to Wire Gauge Conversion Chart

Use this chart to select the best drill bit size for the wire you're using.

Last edited: 10/29/2020
This comprehensive includes Brown & Sharpe, millimeter and inch measurements, and the corresponding drill bit size.
drill size B&S mm inches
  0 8.26 .325 21/64
  1 7.34 .289 9/32
  2 6.52 .257 1/4
1 3 5.81 .229 7/32
6 4 5.18 .204 13/64
15 5 4.62 .182 3/16
20 6 4.11 .162 5/32
27 7 3.66 .144 9/64
30 8 3.25 .128 1/8
  9 2.90 .114  
38 10 2.59 .102  
43 11 2.31 .091  
46 12 2.06 .081 5/64
50 13 1.83 .072  
51 14 1.63 .064 1/16
52 15 1.45 .057  
54 16 1.30 .051  
55 17 1.14 .045 3/64
56 18 1.02 .040  
60 19 0.914 .036  
65 20 0.812 .032 1/32
67 21 0.711 .028  
70 22 0.635 .025  
71 23 0.558 .022  
74 24 0.508 .020  
75 25 0.457 .018  
77 26 0.406 .016 1/64
78 27 0.355 .014  
79 28 0.304 .012  
80 29 0.279 .011  
  30 0.254 .010  
Diagram of wire compared to required drill size