# Bare Solid Copper Wire Properties & Gauge Conversions

Values presented here are standards available for many independent publications, but ultimately they all originate from the American Wire Gauge (AWG) system (also aka the Brown and Sharp - B&S - gauge). It has been in existence since the mid 1800s in the U.S. and Canada. Dimensions apply to most solid cylindrical rods regardless of material - copper, aluminum, plastic, carbon fiber, etc.

Note that as wire gauge number is increased the wire diameter decreases. Although it might seem somewhat backward, there is a good reason for it. Originally, it was related to the number of time a wire needed to be drawn through an extraction die in order to achieve the final wire size.

By definition, 36 AWG* is 0.0050 inches in diameter, and 0000 (four-ought)* is 0.4600 inches in diameter. The ratio of these diameters is 92, and there are 40 gauge sizes from #36 to #0000, or 39 steps. Using this ratio, wire gauge sizes vary geometrically according to the following formula: The diameter of a 36 AWG wire is:

Those equations were used to calculate the values in the table below. Note that for one-ought cable you plug in n=0, for two-ought plug in n=-1, for three-ought plug in n=-2, and for four-ought plug in n=-3.

Accordingly, the ASTM B 258-02 standard defines the ratio between successive sizes to be the 39th root of 92, or approximately 1.1229322.

Stranding designation of a/b means a number of b gauge wires. E.g., 7/44 means 7 strands of 44 AWG solid wire.

Note: Just a 3 dB change in power represents a doubling (or halving) of power, a change of 3 wire sizes represents approximately a doubling (or halving) of cross-sectional area.

See wire gauge conversion chart at bottom of page. Values given at 25 °C, and are based on ideal parameters of pure copper. Here is a table of fusing current of various wire sizes.

A circular mil is the cross-sectional area of a circle with a diameter of 1 mil (1/000th of an inch). NIST lists the density of pure copper as 8.92E+00 g/cm3, and is used here to calculate weight.

 AWG(solid) Approx. O.D. CircularMil Area Weight(lbs/1000 ft) Weight(kg/km) Resistance(Ω/1000 ft) Resistance(Ω/km) MaxCurrent(A) Inches mm 40 0.003145 0.07988 9.888 0.0299 0.0445 1049 3442 0.09 39 0.003531 0.08969 12.47 0.0377 0.0562 832 2729 0.11 38 0.003965 0.1007 15.72 0.0476 0.0708 660 2164 0.13 37 0.004453 0.1131 19.83 0.0600 0.0893 523 1716 0.17 36* 0.005000 0.1270 25.00 0.0757 0.113 415 1361 0.21 35 0.005614 0.1426 31.52 0.0954 0.142 329 1079 0.27 34 0.006304 0.1601 39.75 0.120 0.179 261 856 0.33 33 0.007080 0.1798 50.13 0.152 0.226 207 679 0.43 32 0.007950 0.2019 63.21 0.191 0.285 164 538 0.53 31 0.007950 0.2268 79.70 0.241 0.359 130 427 0.7 30 0.01003 0.2548 100.5 0.304 0.453 103 339 0.86 29 0.01126 0.2860 126.7 0.384 0.571 81.8 268 1.2 28 0.01246 0.3211 159.8 0.484 0.720 64.8 213 1.4 27 0.01419 0.3604 201.5 0.610 0.908 51.5 169 1.7 26 0.01594 0.4049 254.1 0.769 1.14 40.8 134 2.2 25 0.01790 0.4547 320.4 0.970 1.44 32.4 106 2.7 24 0.02010 0.5105 404.0 1.22 1.82 25.7 84.2 3.5 23 0.02257 0.5733 509.5 1.54 2.29 20.4 66.8 4.7 22 0.02535 0.6439 642.4 1.95 2.89 16.1 53.0 7 21 0.02846 0.7229 810.1 2.45 3.65 12.8 42.0 9 20 0.03196 0.8118 1022 3.09 4.60 10.2 33.3 11 19 0.03589 0.9116 1288 3.90 5.80 8.05 26.4 14 18 0.0403 1.024 1624 4.92 7.32 6.39 20.9 16 17 0.04526 1.150 2048 6.20 9.23 5.06 16.6 19 16 0.05082 1.291 2583 7.82 11.6 4.02 13.2 22 15 0.05707 1.450 3257 9.86 14.7 3.18 10.4 28 14 0.06408 1.628 4107 12.4 18.5 2.53 8.28 32 13 0.07196 1.828 5178 15.7 23.3 2.00 6.57 35 12 0.08081 2.053 6530 19.8 29.4 1.59 5.21 41 11 0.09074 2.305 8234 24.9 37.1 1.26 4.13 47 10 0.1019 2.588 10380 31.4 46.8 0.999 3.28 55 9 0.1144 2.906 13090 39.6 59.0 0.792 2.60 64 8 0.1285 3.264 16510 50.0 74.4 0.628 2.06 73 7 0.1443 3.665 20820 63.0 93.8 0.498 1.63 89 6 0.1620 4.115 26250 79.5 118 0.395 1.30 101 5 0.1819 4.620 33100 100 149 0.313 1.03 118 4 0.2043 5.189 41740 126 188 0.249 0.815 135 3 0.2294 5.827 52640 159 237 0.197 0.646 158 2 0.2576 6.543 66370 201 299 0.156 0.512 181 1 0.2893 7.348 83690 253 377 0.124 0.407 211 0 0.3249 8.252 105500 320 475 0.098 0.323 328 00 0.3648 9.266 133100 403 599 0.078 0.256 283 000 0.4096 10.40 167800 508 756 0.062 0.203 245 0000* 0.4600 11.68 211600 641 953 0.049 0.161

Wire Gauge Conversions to Diameter in Inches

All Units Are in Inches

 GAUGE # AWG W & M SWG BWG U.S. Standard 7/0 0.6513 0.490 0.500 0.5000 6/0 0.5800 0.460 0.464 0.4688 5/0 0.5165 0.430 0.432 0.4375 4/0 0.4600 0.3938 0.400 0.454 0.4063 3/0 0.4096 0.3625 0.372 0.425 0.3750 2/0 0.3648 0.3310 0.348 0.380 0.3438 1/0 0.3249 0.3065 0.324 0.340 0.3125 1 0.2893 0.2830 0.300 0.300 0.2813 2 0.2576 0.2625 0.276 0.284 0.2656 3 0.2294 0.2437 0.252 0.259 0.2391 4 0.2043 0.2253 0.232 0.238 0.2242 5 0.1819 0.2070 0.212 0.220 0.2092 6 0.1620 0.1920 0.192 0.203 0.1943 7 0.1443 0.1770 0.176 0.180 0.1793 8 0.1285 0.1620 0.160 0.165 0.1644 9 0.1144 0.1483 0.144 0.148 0.1495 10 0.1019 0.1350 0.128 0.134 0.1345 11 0.0907 0.1205 0.116 0.120 0.1196 12 0.0808 0.1055 0.104 0.109 0.1046 13 0.0719 0.0915 0.092 0.095 0.0897 14 0.0641 0.0800 0.080 0.083 0.0747 15 0.0571 0.0720 0.072 0.072 0.0673 16 0.0508 0.0625 0.064 0.065 0.0598 17 0.04526 0.054 0.056 0.058 0.0538 18 0.04030 0.0475 0.048 0.049 0.0478 19 0.03589 0.0410 0.040 0.042 0.0418 20 0.03196 0.0348 0.036 0.035 0.0359 21 0.02846 0.03175 0.032 0.032 0.0329 22 0.02535 0.0286 0.028 0.028 0.0299 23 0.02257 0.0258 0.024 0.025 0.0269 24 0.02010 0.0230 0.022 0.022 0.0239 25 0.01790 0.0204 0.020 0.020 0.0209 26 0.01594 0.0181 0.018 0.018 0.0179 27 0.01420 0.0173 0.0164 0.016 0.0164 28 0.01264 0.0162 0.0148 0.014 0.0149 29 0.01126 0.0150 0.0136 0.013 0.0135 30 0.0103 0.014 0.0124 0.012 0.0120 31 0.00893 0.0132 0.0116 0.010 0.0109 32 0.00795 0.0128 0.0108 0.009 0.0102 33 0.00708 0.0118 0.0100 0.008 0.0094 34 0.00630 0.0104 0.0092 0.007 0.0086 35 0.00561 0.0095 0.0084 0.005 0.0078 36 0.00500 0.0090 0.0076 0.004 0.0070 37 0.00445 0.0085 0.0068 38 0.00396 0.0080 0.0060 39 0.00353 0.0075 0.0052 40 0.00314 0.007 0.0048 41 0.00279 0.0066 0.0044 42 0.00249 0.0062 0.0040 43 0.00221 0.0060 0.0036 44 0.00198 0.0058 0.0032 45 0.00176 0.0055 0.0028 46 0.00157 0.0052 0.0024 47 0.00140 0.0050 0.0016 48 0.00124 0.0048 0.0012 49 0.00111 0.0046 0.0010 50 0.00099 0.0044 51 0.00088 52 0.00078 53 0.00070 54 0.00060 55 0.00050 56 0.00040 AWG = American Wire Gauge (Brown & Sharpe) W & M = Washburn & Moen (steel wire gauge) SWG = Imperial Standard Wire Gauge BWG = Birmingham or Stubs Wire Gauge US Standard = United States Standard (Revised)