# Practical Electronics/SWG

The thickness of a wire is often given as a Standard Wire Gauge, or SWG. This is number from 0000000 or 7/0 (thickest) to 50 (thinnest). The gauge of most wire used in electronics is between 20 and 30. Often, a wire gauge will be stated followed by "swg", so 26 swg, etc.
It is very important that you do not confuse SWG with AWG, which means American Wire Gauge - although fairly similar, it is a different system of sizing wires.
The table below lists the SWG gauges, along with the diameter in inches and millimetres.

# WARNNIG!!! This table appears to be incorrect. From measurement and also from another website (that I am unable to link due to policies) a copper wire of about 0.127mm diameter has a resistance of 1426 Ohms/km, whereas this table above states that a thicker wire of 0.132mm diameter has a resistance of 4130 Ohms/km, much higher. I suggest that anyone using this table for important work should check elsewhere. WARNING!!! WRONG!!!

| Standard Wire Gauge | Diameter | Diameter | Turns of wire | Turns of wire | Cross-sectional area | Cross-sectional area | Res. per length (for copper wire) | Res. per length (for copper wire) | Mass per length | Mass per length | Current Capacity (A) | Current Capacity (A) |
| Standard Wire Gauge | in | mm | in$^{−1}$ | mm$^{−1}$ | kcmil | mm$^2$ | Ω/kft | Ω/km | lb/ft | kg/m | 750 cmil/A | 500 cmil/A |
| 0000000 (7/0) | 0.500 | 12.7 | 2.00 | 0.0787 | 250 | 127 | 0.136 | 0.447 | 0.759 | 1.13 | 333 | 500 |
| 000000 (6/0) | 0.464 | 11.8 | 2.16 | 0.0848 | 215 | 109 | 0.158 | 0.519 | 0.654 | 0.973 | 287 | 431 |
| 00000 (5/0) | 0.432 | 11.0 | 2.31 | 0.0911 | 187 | 94.6 | 0.182 | 0.598 | 0.567 | 0.844 | 249 | 373 |
| 0000 (4/0) | 0.400 | 10.2 | 2.50 | 0.0984 | 160 | 81.1 | 0.213 | 0.698 | 0.486 | 0.723 | 213 | 320 |
| 000 (3/0) | 0.372 | 9.45 | 2.69 | 0.106 | 138 | 70.1 | 0.246 | 0.807 | 0.420 | 0.625 | 185 | 277 |
| 00 (2/0) | 0.348 | 8.84 | 2.87 | 0.113 | 121 | 61.4 | 0.281 | 0.922 | 0.368 | 0.547 | 161 | 242 |
| 0 (1/0) | 0.324 | 8.23 | 3.09 | 0.122 | 105 | 53.2 | 0.324 | 1.06 | 0.319 | 0.474 | 140 | 210 |
| 1 | 0.300 | 7.62 | 3.33 | 0.131 | 90.0 | 45.6 | 0.378 | 1.24 | 0.273 | 0.407 | 120 | 180 |
| 2 | 0.276 | 7.01 | 3.62 | 0.143 | 76.2 | 38.6 | 0.447 | 1.47 | 0.231 | 0.344 | 102 | 152 |
| 3 | 0.252 | 6.40 | 3.97 | 0.156 | 63.5 | 32.2 | 0.536 | 1.76 | 0.193 | 0.287 | 84.7 | 127 |
| 4 | 0.232 | 5.89 | 4.31 | 0.170 | 53.8 | 27.3 | 0.632 | 2.07 | 0.163 | 0.243 | 71.8 | 108 |
| 5 | 0.212 | 5.38 | 4.72 | 0.186 | 44.9 | 22.8 | 0.757 | 2.48 | 0.137 | 0.203 | 59.9 | 89.9 |
| 6 | 0.192 | 4.88 | 5.21 | 0.205 | 36.9 | 18.7 | 0.923 | 3.03 | 0.112 | 0.167 | 49.2 | 73.7 |
| 7 | 0.176 | 4.47 | 5.68 | 0.224 | 31.0 | 15.7 | 1.10 | 3.60 | 0.0941 | 0.140 | 41.3 | 62.0 |
| 8 | 0.160 | 4.06 | 6.25 | 0.246 | 25.6 | 13.0 | 1.33 | 4.36 | 0.0778 | 0.116 | 34.1 | 51.2 |
| 9 | 0.144 | 3.66 | 6.94 | 0.273 | 20.7 | 10.5 | 1.64 | 5.38 | 0.0630 | 0.0937 | 27.6 | 41.5 |
| 10 | 0.128 | 3.25 | 7.81 | 0.308 | 16.4 | 8.30 | 2.08 | 6.81 | 0.0498 | 0.0741 | 21.8 | 32.8 |
| 11 | 0.116 | 2.95 | 8.62 | 0.339 | 13.5 | 6.82 | 2.53 | 8.30 | 0.0409 | 0.0608 | 17.9 | 26.9 |
| 12 | 0.104 | 2.64 | 9.62 | 0.379 | 10.8 | 5.48 | 3.15 | 10.3 | 0.0329 | 0.0489 | 14.4 | 21.6 |
| 13 | 0.0920 | 2.34 | 10.9 | 0.428 | 8.46 | 4.29 | 4.02 | 13.2 | 0.0257 | 0.0383 | 11.3 | 16.9 |
| 14 | 0.0800 | 2.03 | 12.5 | 0.492 | 6.40 | 3.24 | 5.32 | 17.4 | 0.0194 | 0.0289 | 8.53 | 12.8 |
| 15 | 0.0720 | 1.83 | 13.9 | 0.547 | 5.18 | 2.63 | 6.56 | 21.5 | 0.0157 | 0.0234 | 6.91 | 10.4 |
| 16 | 0.0640 | 1.63 | 15.6 | 0.615 | 4.10 | 2.08 | 8.31 | 27.3 | 0.0124 | 0.0185 | 5.46 | 8.19 |
| 17 | 0.0560 | 1.42 | 17.9 | 0.703 | 3.14 | 1.59 | 10.9 | 35.6 | 0.00952 | 0.0142 | 4.18 | 6.27 |
| 18 | 0.0480 | 1.22 | 20.8 | 0.820 | 2.30 | 1.17 | 14.8 | 48.5 | 0.00700 | 0.0104 | 3.07 | 4.61 |
| 19 | 0.0400 | 1.02 | 25.0 | 0.984 | 1.60 | 0.811 | 21.3 | 69.8 | 0.00486 | 0.00723 | 2.13 | 3.20 |
| 20 | 0.0360 | 0.914 | 27.8 | 1.09 | 1.30 | 0.657 | 26.3 | 86.1 | 0.00394 | 0.00586 | 1.73 | 2.59 |
| 21 | 0.0320 | 0.813 | 31.3 | 1.23 | 1.02 | 0.519 | 33.2 | 109 | 0.00311 | 0.00463 | 1.37 | 2.05 |
| 22 | 0.0280 | 0.711 | 35.7 | 1.41 | 0.784 | 0.397 | 43.4 | 142 | 0.00238 | 0.00354 | 1.05 | 1.57 |
| 23 | 0.0240 | 0.610 | 41.7 | 1.64 | 0.576 | 0.292 | 59.1 | 194 | 0.00175 | 0.00260 | 0.768 | 1.15 |
| 24 | 0.0220 | 0.559 | 45.5 | 1.79 | 0.484 | 0.245 | 70.3 | 231 | 0.00147 | 0.00219 | 0.645 | 0.968 |
| 25 | 0.0200 | 0.508 | 50.0 | 1.97 | 0.400 | 0.203 | 85.1 | 279 | 0.00121 | 0.00181 | 0.533 | 0.800 |
| 26 | 0.0180 | 0.457 | 55.6 | 2.19 | 0.324 | 0.164 | 105 | 345 | 984µ | 0.00146 | 0.432 | 0.648 |
| 27 | 0.0164 | 0.417 | 61.0 | 2.40 | 0.269 | 0.136 | 127 | 415 | 817µ | 0.00122 | 0.359 | 0.538 |
| 28 | 0.0148 | 0.376 | 67.6 | 2.66 | 0.219 | 0.111 | 155 | 510 | 665µ | 990µ | 0.292 | 0.438 |
| 29 | 0.0136 | 0.345 | 73.5 | 2.89 | 0.185 | 0.0937 | 184 | 604 | 562µ | 836µ | 0.247 | 0.370 |
| 30 | 0.0124 | 0.315 | 80.6 | 3.18 | 0.154 | 0.0779 | 221 | 726 | 467µ | 695µ | 0.205 | 0.308 |
| 31 | 0.0116 | 0.295 | 86.2 | 3.39 | 0.135 | 0.0682 | 253 | 830 | 409µ | 608µ | 0.179 | 0.269 |
| 32 | 0.0108 | 0.274 | 92.6 | 3.65 | 0.117 | 0.0591 | 292 | 957 | 354µ | 527µ | 0.156 | 0.233 |
| 33 | 0.0100 | 0.254 | 100 | 3.94 | 0.100 | 0.0507 | 340 | 1120 | 304µ | 452µ | 0.133 | 0.200 |
| 34 | 0.00920 | 0.234 | 109 | 4.28 | 0.0846 | 0.0429 | 402 | 1320 | 257µ | 383µ | 0.113 | 0.169 |
| 35 | 0.00840 | 0.213 | 119 | 4.69 | 0.0706 | 0.0358 | 482 | 1580 | 214µ | 319µ | 0.0941 | 0.141 |
| 36 | 0.00760 | 0.193 | 132 | 5.18 | 0.0578 | 0.0293 | 589 | 1930 | 175µ | 261µ | 0.0770 | 0.116 |
| 37 | 0.00680 | 0.173 | 147 | 5.79 | 0.0462 | 0.0234 | 736 | 2410 | 140µ | 209µ | 0.0617 | 0.0925 |
| 38 | 0.00600 | 0.152 | 167 | 6.56 | 0.0360 | 0.0182 | 945 | 3100 | 109µ | 163µ | 0.0480 | 0.0720 |
| 39 | 0.00520 | 0.132 | 192 | 7.57 | 0.0270 | 0.0137 | 1260 | 4130 | 82.1µ | 122µ | 0.0361 | 0.0541 |
| 40 | 0.00480 | 0.122 | 208 | 8.20 | 0.0230 | 0.0117 | 1480 | 4850 | 70.0µ | 104µ | 0.0307 | 0.0461 |
| 41 | 0.00440 | 0.112 | 227 | 8.95 | 0.0194 | 0.00981 | 1760 | 5770 | 58.8µ | 87.5µ | 0.0258 | 0.0387 |
| 42 | 0.00400 | 0.102 | 250 | 9.84 | 0.0160 | 0.00811 | 2130 | 6980 | 48.6µ | 72.3µ | 0.0213 | 0.0320 |
| 43 | 0.00360 | 0.0914 | 278 | 10.9 | 0.0130 | 0.00657 | 2630 | 8610 | 39.4µ | 58.6µ | 0.0173 | 0.0259 |
| 44 | 0.00320 | 0.0813 | 313 | 12.3 | 0.0102 | 0.00519 | 3320 | 10900 | 31.1µ | 46.3µ | 0.0137 | 0.0205 |
| 45 | 0.00280 | 0.0711 | 357 | 14.1 | 0.00784 | 0.00397 | 4340 | 14200 | 23.8µ | 35.4µ | 0.0105 | 0.0157 |
| 46 | 0.00240 | 0.0610 | 417 | 16.4 | 0.00576 | 0.00292 | 5910 | 19400 | 17.5µ | 26.0µ | 0.00768 | 0.0115 |
| 47 | 0.00200 | 0.0508 | 500 | 19.7 | 0.00400 | 0.00203 | 8510 | 27900 | 12.1µ | 18.1µ | 0.00533 | 0.00800 |
| 48 | 0.00160 | 0.0406 | 625 | 24.6 | 0.00256 | 0.00130 | 13300 | 43600 | 7.78µ | 11.6µ | 0.00341 | 0.00512 |
| 49 | 0.00120 | 0.0305 | 833 | 32.8 | 0.00144 | 730µ | 23600 | 77500 | 4.37µ | 6.51µ | 0.00192 | 0.00288 |
| 50 | 0.00100 | 0.0254 | 1000 | 39.4 | 0.00100 | 507µ | 34000 | 112000 | 3.04µ | 4.52µ | 0.00133 | 0.00200 |
| Notes: | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. | All values are rounded to three significant figures. Values less than 1×10$^{−6}$ are shown with appropriate SI prefixes to avoid a large number of leading zeros. The IACS value of 58.0 MS/m is used as the conductivity of copper. These calculations do not take into account AC effects such as the skin effect - perform suitable calculations before using in a high-frequency application. Grid mains frequencies (50–60 Hz) should not have a noticeable effect, as the skin depth is over 8mm. A density of copper of 8920 kg/m$^3$ is used to derive the mass An allowance of 750 cmil/A is generally sufficient for calculating current capacity. The more relaxed 500 cmil/A is an absolute maximum. The values are guidelines − exact values will depend on the type of wire and operating conditions such as ambient temperature, thermal conductivity of the surroundings. |
| This box: view • talk • |||||||||||||
This table appears to be incorrect. From measurement and also from another website (that I am unable to link due to policies) a copper wire of about 0.127mm diameter has a resistance of 1426 Ohms/km, whereas this table above states that a thicker wire of 0.132mm diameter has a resistance of 4130 Ohms/km, much higher. I suggest that anyone using this table for important work should check elsewhere.

## External links

* Wikipedia article on SWG
the value under "current capacity/A" shown in the table as "750 kcmil/A" & "500 kcmil/A" should read as "750 cmil/A" & "500 cmil/A" instead. this can be checked by dividing any value under "area in kcmil" with 750 cmil/A or by 500 cmil/A the result in Current capacity column will match. it is not matching now. moreover the column "current capacity/A" should read as " current capacity in A".
The values for resistance in ohms per kft are not correct. They appear to have been derived from the figures for ohms per km, which are correct, by multiplying that figure by 3.28 (the conversion factor from metres to feet) rather than dividing by 3.28.