# wire gauges

We also provide the following conversion tables:

## Sizing wire

The way wire is made leads to a “natural” series of sizes. A rod (made in a rolling mill) is pulled through a hole whose diameter is slightly smaller than the rod's. This process is repeated through ever-smaller holes until the wire is as fine as desired.

To reduce the number of steps for economy's sake, the manufacturer would like the change in size at each drawing to be as large as possible; on the other hand if the change in size is too great the wire will break while being drawn. Older wire gauges like the Birmingham, Washburn & Moen, and Lancashire came from calling the wire from the first drawing number 1, from the second drawing #2, and so on. Note that the higher the number, the finer the wire.

### sources

1

It is impossible to draw a wire to an exact size. Ordinary practice is to draw a No. 10 B. & S. wire between 101 and 103 mils. The resulting wire may average 102 or 101.9 mils, or something different from either. A table calculated on the exact size is, therefore, as nearly right as though ordinary shop sizes were used. The weight and resistance of an actual wire will very seldom correspond with any table.

Wire in Electrical Construction.
Trenton, NJ: John A. Roebling's Sons Company, 1916.
Page 75.

## A table comparing diameters of some common gauges

More complete information (cross sectional area, weight, resistance) on these gauges can be found by following the links in the contents list above left.

Note that 4/0 (pronounced “four aught”) is an abbreviation for 0000, 2/0 for 00, and so on. The colored verticals are simply an aid to orientation. Click for a more printable version (pdf).

Common Wire Gauges, Based on Diameter in Inches.
Gauge American
or
Brown &
Sharpe
Wire
Gauge
Birming-
ham

or
Stubs'
Iron
Wire
Stubs'
Steel
Wire
Gauge
Wash-
burn
&
Moen;
Roebling;
or
American
Steel
and
Wire Co.
Imperial
Wire
Gauge
Whit-
worth's
Steel Wire
Gauge,
Waterbury
Co.,
1917
9/0  —  — 0.005
8/0  —  — 0.0055
7/0  0.4900 0.5000 0.006
6/0 0.5800  0.4615 0.4640 0.0065
5/0 0.5165 0.500  0.4305 0.4320 0.007
4/0 0.4600 0.454 0.3938 0.4000 0.0075
3/0 0.4096 0.425 0.3625 0.3720 0.008
2/0 0.3648 0.380 0.3310 0.3480 0.0085
0 0.3249 0.340 0.3065 0.3240 0.009
1 0.2893 0.300 0.227 0.2830 0.3000 0.001 0.010
2 0.2576 0.284 0.219 0.2625 0.2760 0.002 0.011
3 0.2294 0.259 0.212 0.2437 0.2520 0.003 0.012
4 0.2043 0.238 0.207 0.2253 0.2320 0.004 0.013
5 0.1819 0.220 0.204 0.2070 0.2120 0.005 0.014
6 0.1620 0.203 0.201 0.1920 0.1920 0.006 0.016
7 0.1443 0.180 0.199 0.1770 0.1760 0.007 0.018
8 0.1285 0.165 0.197 0.1620 0.1600 0.008 0.020
9 0.1144 0.148 0.194 0.1483 0.1440 0.009 0.022
10 0.1019 0.134 0.191 0.1350 0.1280 0.010 0.024
11 0.0907 0.120 0.188 0.1205 0.1160 0.011 0.026
12 0.0808 0.109 0.185 0.1055 0.1040 0.012 0.028
13 0.0720 0.095 0.182 0.0915 0.0920 0.013 0.030
14 0.0641 0.083 0.180 0.0800 0.0800 0.014 0.032
15 0.0571 0.072 0.178 0.0720 0.0720 0.015 0.034
16 0.0508 0.065 0.175 0.0625 0.0640 0.016 0.036
17 0.0453 0.058 0.172 0.0540 0.0560 0.017 0.038
18 0.0403 0.049 0.168 0.0475 0.0480 0.018 0.040
19 0.0359 0.042 0.164 0.0410 0.0400 0.019 0.042
20 0.0320 0.035 0.161 0.0348 0.0360 0.020 0.044
21 0.0285 0.032 0.157 0.03175 0.0320 0.021 0.046
22 0.0253 0.028 0.155 0.0286 0.0280 0.022 0.048
23 0.0226 0.025 0.153 0.0258 0.0240 0.023 0.051
24 0.0201 0.022 0.151 0.0230 0.0220 0.024 0.055
25 0.0179 0.020 0.148 0.0204 0.0200 0.025 0.059
26 0.0159 0.018 0.146 0.0181 0.0180 0.026 0.063
27 0.0142 0.016 0.143 0.0173 0.0164 0.027 0.067
28 0.0126 0.014 0.139 0.0162 0.0149 0.028 0.071
29 0.0113 0.013 0.134 0.0150 0.0136 0.029 0.074
30 0.0100 0.012 0.127 0.0140 0.0124 0.030 0.078
31 0.0089 0.010 0.120 0.0132 0.0116 0.031 0.082
32 0.0080 0.009 0.115 0.0128 0.0108 0.032 0.086
33 0.0071 0.008 0.112 0.0118 0.0100 0.033 0.090
34 0.0063 0.007 0.110 0.0104 0.0092 0.034 0.094
35 0.0056 0.005 0.108 0.0095 0.0084 0.035 0.098
36 0.0050 0.004 0.106 0.0090 0.0076 0.036 0.102
37 0.0045 0.103 0.0068 0.037 0.106
38 0.0040 0.101 0.0060 0.038 0.112
39 0.0035 0.099 0.0052 0.039 0.118
40 0.0031 0.097 0.0048 0.040 0.125
41 0.0028 0.095  — 0.0044 0.041 0.132
42 0.0025 0.092  — 0.0040 0.042 0.139
43 0.0022 0.088  — 0.0036 0.043 0.146
44 0.00198 0.085  — 0.0032 0.044 0.153
45 0.00176 0.081  — 0.0028 0.045 0.160
46 0.00157 0.079 0.0024 0.046
47 0.00140 0.077 0.0020 0.047
48 0.00124 0.075 0.0016 0.048
49 0.001108 0.072 0.0012 0.049
50 0.00099 0.069 0.0010 0.050
51   0.066 0.051
52 0.063  0.052
53   0.058  0.053
54 0.055  0.054
55 0.050 0.055
56 0.045 0.056
57     0.042     0.057
58     0.041     0.058
59     0.040     0.059
60     0.039     0.060
61     0.038     0.061
62     0.037     0.062
63     0.036     0.063
64     0.035     0.064
65     0.033     0.065
66     0.032     0.066
67     0.031     0.067
68     0.030     0.068
69     0.029     0.069
70     0.027     0.070
71     0.026     0.071
72     0.024     0.072
73     0.023     0.073
74     0.022     0.074
75     0.020     0.075
76     0.018     0.076
77     0.016     0.077
78     0.015     0.078
79     0.014     0.079
80     0.013     0.080

## Morse Twist Drill gauge

It is a copy of the Lancashire gauge, the sizes being taken from wire and rod imported from Britain.

## Stub's Steel Wire gauge

Used for drill rod and tool steel wire. It is the basis of, though not identical to, the numbered sizes of American Standard twist drills. Note that there is also a Stub's Iron Wire Gauge.

## Old English wire gage

Also known as the London gage. 19th century. Used for brass and copper wire, especially brass wire for weaving.