# American wire gauge

American wire gauge (AWG), also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used in the United States and other countries, especially for nonferrous, electrically conducting wire. The steel industry uses a different numbering system for their wire thickness gauges (for example, W&M Wire Gauge or US Steel Wire Gauge or the different Music Wire Gauge) so data below does not apply to steel wire.

Increasing gauge numbers give decreasing wire diameters, which is similar to many other non-metric gauging systems. This seemingly-counterintuitive numbering is derived from the fact that the gauge number is related to the number of drawing operations that must be used to produce a given gauge of wire; very fine wire (for example, 30 gauge) requires far more passes through the drawing dies than does 0 gauge wire.

Note that for gauges 5 through about 14, the wire gauge is effectively the number of bare solid wires that, when placed side by side, span 1 inch. That is, 8 gauge is about 1/8 inches in diameter.

In the same fashion, AWG is also commonly used to specify body piercing jewelry sizes, especially smaller sizes.[1]

## Formula

By definition, No. 36 AWG is 0.005 inches diameter, and No. 0000 is 0.46 inches diameter. The ratio of these sizes is 92, and between them are 38 sizes, with equal ratios between each adjacent pair of sizes. (The 40 different sizes result in 39 size changes.) (Sizes with multiple zeros are successively larger than No. 0 and can be denoted using "number of zeros/0", for example 4/0 for 0000.) Therefore, the diameter of a No. n AWG wire is

$d_n = 0.005~\mathrm{inch} \times 92 ^ \frac{36-n}{39}$

and its cross-section area is

$A_n = \frac{\pi}{4} d_n^2 = 0.000019635~\mathrm{inch}^2 \times 92 ^ \frac{36-n}{19.5}$.

For an m/0 AWG wire, use n = −(m−1) in the above formulas. For instance, for No. 0000 or 4/0, use n = −3.

The ratio between successive sizes is the 39th root of 92, or approximately 1.1229322.[2]

The sixth power of this ratio is very close to 2, which means for an increase in six gauge numbers, the wire diameter is changed by a ratio of 2 (No. 10 is about one-half the diameter of No. 4 AWG). A decrease of three gauge numbers doubles the area of a wire. A decrease of ten gauge numbers, for example from No. 10 to 1/0, multiplies the area and weight by approximately 10 and reduces the resistance by approximately 10.

## Table of AWGs and approximate corresponding sizes

The table below shows various data including both the resistance of the various wire gauges and the allowable current (ampacity) based on plastic insulation. The diameter information in the table applies to solid wires. Stranded wires are calculated by calculating the equivalent cross sectional copper area. The table below assumes DC, or AC frequencies equal to or less than 60 Hz, and does not take skin effect into account. Turns of wire is on a best-case scenario when winding tightly packed coils.

AWG Diameter Turns of wire Area Copper
resistance
Copper wire
current rating
with 60°C raceway (A)
Approximate
stranded metric
equivalents
(inch) (mm) (per inch) (per cm) (kcmil) (mm²) (Ω/km) (mΩ/ft)[3]
0000 (4/0) 0.460 11.7 2.17 0.856 212 107 0.16* 0.049* 195
000 (3/0) 0.410 10.4 2.44 0.961 168 85.0 0.2* 0.062* 165
00 (2/0) 0.365 9.27 2.74 1.08 133 67.4 0.25* 0.077* 145
0 (1/0) 0.325 8.25 3.08 1.21 106 53.5 ~0.3281 ~0.1 125
1 0.289 7.35 3.46 1.36 83.7 42.4 0.4* 0.12* 110
2 0.258 6.54 3.88 1.53 66.4 33.6 0.5* 0.15* 95
3 0.229 5.83 4.36 1.72 52.6 26.7 85 196/0.4
4 0.204 5.19 4.89 1.93 41.7 21.2 0.8* 0.24* 70
5 0.182 4.62 5.50 2.16 33.1 16.8 126/0.4
6 0.162 4.12 6.17 2.43 26.3 13.3 1.5* 0.47* 55
7 0.144 3.66 6.93 2.73 20.8 10.5 80/0.4
8 0.128 3.26 7.78 3.06 16.5 8.37 2.2* 0.67* 40
9 0.114 2.91 8.74 3.44 13.1 6.63 >84/0.3
10 0.102 2.59 9.81 3.86 10.4 5.26 3.2772 0.9989 30 <84/0.3
11 0.0907 2.30 11.0 4.34 8.23 4.17 4.1339 1.26 56/0.3
12 0.0808 2.05 12.4 4.87 6.53 3.31 5.21 1.588 20
13 0.0720 1.83 13.9 5.47 5.18 2.62 6.572 2.003 50/0.25
14 0.0641 1.63 15.6 6.14 4.11 2.08 8.284 2.525 15
15 0.0571 1.45 17.5 6.90 3.26 1.65 10.45 3.184 >30/0.25
16 0.0508 1.29 19.7 7.75 2.58 1.31 13.18 4.016 10 <30/0.25
17 0.0453 1.15 22.1 8.70 2.05 1.04 16.614 5.064 32/0.2
18 0.0403 1.02 24.8 9.77 1.62 0.823 20.948 6.385 5[4] >24/0.2
19 0.0359 0.912 27.9 11.0 1.29 0.653 26.414 8.051 <24/0.2
20 0.0320 0.812 31.3 12.3 1.02 0.518 33.301 10.15 3.3 16/0.2
21 0.0285 0.723 35.1 13.8 0.810 0.410 41.995 12.8
22 0.0253 0.644 39.5 15.5 0.642 0.326 52.953 16.14 2.1 7/0.25
23 0.0226 0.573 44.3 17.4 0.509 0.258 66.798 20.36
24 0.0201 0.511 49.7 19.6 0.404 0.205 84.219 25.67 1.3 1/0.5, 7/0.2, 30/0.1
25 0.0179 0.455 55.9 22.0 0.320 0.162 106.201 32.37
26 0.0159 0.405 62.7 24.7 0.254 0.129 133.891 40.81 0.8 7/0.15
27 0.0142 0.361 70.4 27.7 0.202 0.102 168.865 51.47
28 0.0126 0.321 79.1 31.1 0.160 0.0810 212.927 64.9 0.5
29 0.0113 0.286 88.8 35.0 0.127 0.0642 268.471 81.83
30 0.0100 0.255 99.7 39.3 0.101 0.0509 338.583 103.2 ~0.3[citation needed] 1/0.25, 7/0.1
31 0.00893 0.227 112 44.1 0.0797 0.0404 426.837 130.1
32 0.00795 0.202 126 49.5 0.0632 0.0320 538.386 164.1 ~0.2[citation needed] 1/0.2, 7/0.08
33 0.00708 0.180 141 55.6 0.0501 0.0254 678.806 206.9
34 0.00630 0.160 159 62.4 0.0398 0.0201 833 260.9 ~0.12[citation needed]
35 0.00561 0.143 178 70.1 0.0315 0.0160 1085.958 331
36 0.00500 0.127 200. 78.7 0.0250 0.0127 1360.892 414.8 ~0.074[citation needed]
37 0.00445 0.113 225 88.4 0.0198 0.0100 1680.118 512.1
38 0.00397 0.101 252 99.3 0.0157 0.00797 2127.953 648.6 ~0.046[citation needed]
39 0.00353 0.0897 283 111 0.0125 0.00632 2781.496 847.8
40 0.00314 0.0799 318 125 0.00989 0.00501 3543.307 1080 ~0.028[citation needed]

(*) insulation included

The "Approximate stranded metric equivalents" column lists commonly available cables in the format "number of strands / diameter of individual strand (mm)" which is the common nomenclature describing cable construction within an overall cross-sectional area. Where a common cable is midway between two AWG sizes, it is listed and being ">" one AWG and "<" another AWG. Cables sold in Europe are normally labeled according to the combined cross section of all strands in mm², which can be compared directly with the Area column.

In the North American electrical industry, conductors larger than 4/0 AWG are generally identified by the area in thousands of circular mils (kcmil), where 1 kcmil = 0.5067 mm². A circular mil is the area of a wire one mil in diameter. One million circular mils is the area of a rod with 1000 mil = 1 inch diameter. An older abbreviation for one thousand circular mils is mcm. The term "mil" is capable of being misinterpreted because the term "mil" is used sometimes as a colloquial term for millimeter, milliliter, and so-forth.

Outside North America, wire sizes for electrical purposes are usually given as the cross sectional area in square millimeters. International standard manufacturing sizes for conductors in electrical cables are defined in IEC 60228.

Note that the area in mm2 may differ somewhat from the numbers given in the table, depending on number of strands etc.

## Pronunciation

AWG is colloquially referred to as gauge and the zeros in large wire sizes are referred to as aught (Template:PronEng). Wire sized 1 AWG is referred to as "one gauge"; similarly, smaller diameters are pronounced "x gauge", where x is the positive integer AWG number. Larger wire (#0 and up) is referred to as "one aught", "two aught" etc, depending on how many zeros are in the AWG rating.[5]

## References

• Donald G. Fink and H. Wayne Beaty, Standard Handbook for Electrical Engineers, Eleventh Edition,McGraw-Hill, New York, 1978, ISBN 0-07-020974-X, page 4-18 and table 4-11.