wire

American Wire Gauge (AWG)
Birmingham Wire Gage
British Standard Wire Gage
Brown & Sharpe Wire Gauge (AWG)
Imperial Wire Gauge
French wire gauges: Jauge de Paris, Jauge Japy
London Gage
Morse Twist Drill Gauge
Needle Wire Gauge
Old English Wire Gage
Standard Wire Gage
Stub's Steel Wire Gauge
Washburn & Moen Wire Gauge
Whitworth's Wire Gauge

Note that 4/0 (pronounced "four aught") is an abbreviation for 0000, 2/0 for 00, and so on. The colored bars are simply to help you locate values. Click for a more printable version (pdf).

Common Wire Gauges Based on Diameter in Inches.
All dimensions 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

Origin of wire sizing

The way wire is made leads to a “natural” series of sizes. A rod (made in a rolling mill) is heated and 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 (see making wire).

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.

Brown & Sharpe, or American Wire gauge (AWG)

Used in the United States since at least the 1880s for wires in all metals except iron and steel. Number 0000 wire is 0.4600 inch in diameter. The diameter of each succeeding size is 0.890525 times the diameter of the previous size. See column 1 of the table above.

ASTM Standard B 258-02, Standard specification for standard nominal diameters and cross-sectional areas of AWG sizes of solid round wires used as electrical conductors.

Washburn & Moen Wire gauge

Also called the Steel Wire Gage, Roebling, and the American Steel and Wire Co. Established about 1830 and named after the Washburn and Moen Manufacturing Company, which was later merged into the American Steel and Wire Co.

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.

Birmingham Wire Gage

The steps are irregular. Departmental sanction by the United States government ended in 1914.

Imperial Wire Gage, or British Standard Gage

Legalized Standard Wire Gauge, Imperial Standard Wire Gauge, or in other countries, simply British Standard. Abbreviated S.G.W. or I.S.G.W. Fixed by order of council August 23, 1883. It was constructed by improving the Birmingham wire gage. Made legal standard March 1, 1884.

Needle Wire gauge

Derived from the Birmingham Wire Gauge. #1 = 18½ B.W.G.; #2 = 19 B.W.G., and so on to #14 = 31 B.W.G. See S. S. Wheeler, Electrical World, Nov. 12, 1887.

Old English wire gage

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

Whitworth’s wire gauge

Also known as Cocker's Wire Gauge. The gauge number is simply the diameter of the wire in thousandths of an inch, for example #1 has a diameter of 0.001 inch.

Edison Standard wire gauge

A standard used in the 19th century by the Edison Electrical Light Company for wires made to carry electric current. The gauge number is the number of thousands of circular mils in the wire's cross section. The cross-sectional area is a much more reasonable than diameter as a basis for sizing electric conductors.