Constructors Corner.
Wire gauge is a measurement of how large a wire is, either in diameter or cross sectional area. This determines the amount of electrical current a wire can safely carry, as well as its electrical resistance and weight per unit of length. Wire gauge is applicable to both electrical and non-electrical wires.
In some applications wire sizes are specified as the cross sectional area of the wire, usually in mm². Advantages of this system include the ability to readily calculate the physical dimensions or weight of wire, ability to take account of non-circular wire, and ease of calculation of electrical properties.
There seem to be as many Wire Gauges as there are stars in the sky! Here I will deal with the most common: AWG and SWG along with the up and coming Metric.
Also known as the "Brown and Sharpe" wire gauge, is used in the United States since at least the 1880s as a standard method of denoting wire diameter for nonferrous, electrically conducting wire. Also used in other countries.
Increasing 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.
Number 0000 (4/0) wire is 0.4600 inch (11.68 mm) in diameter. The diameter of each succeeding size is 0.890525 times the diameter of the previous size.
Sanctioned by the British Board of Trade, British Standard Gauge was formulated by J. Latimer Clark. Fixed by order of council August 23, 1883, it was made by improving on the Birmingham wire gauge. Made legal standard on March 1, 1884.
It differs from the then pre-existing gauges scarcely more than they differ among themselves. It is based on a rational system, the basis being the mil. No. 7/0 (0000000), the largest size, is 0.50 in. (500 mils or 12.7 mm) in diameter, and the smallest, No. 50, is 0.001 in. (1 mil or about 25 µm) in diameter. Between these the diameter, or thickness, diminishes by 10.557%, and the weight diminishes by 20%.
In the Metric Gauge scale, the gauge is 10 times the diameter in millimeters, so a 50 gauge metric wire would be 5 mm in diameter. Note that in AWG and SWG the diameter goes up as the gauge goes down, but for metric gauges it is the opposite. Probably because of this confusion metric sized wire is usually specified in millimeters rather than metric gauges. Metric gauge sizes can also be decimal fractioned, i.e: 12.5 Metric Gauge is one and a quater mm.
Just to confuse the issue even more wire and cable are often quoted as mm² so I have included the mm² values as well.
Generally available mm² sizes are:
1mm², 1.5mm², 2.5mm², 4mm², 6mm²,10mm², 16mm², 25mm², 35mm², 50mm², 70mm², 95mm² and 120mm².
This table does not give current capacity because the current handling of any wire depends on the gauge, insulation, temperature, bundling, etc.
What I have done is to place the wires in order from the largest (top) to smallest (bottom) with their measurements in inch and metric, the measurements are colour coded to make it easier to follow with headings repeated for easy viewing. The dimensions refer to solid, single core wire.
Not all Metric Gauge sizes are included as they are easy to work out.
Obviously if you are making a project and a certain gauge is specified but not to hand use the next larger that you have available.
If you spot any errors feel free to let me know, the information came from several sources and, as is usual in cases like this, some of it disagreed!
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
|---|---|---|---|---|---|
| = | (7/0) 0000000 |
127 | = | 0.50 | 12.7 |
| = | = | 125 | = | 0.4331 | 12.54 |
| = | = | 120 | = | 0.4331 | 12 |
| = | (6/0) 000000 |
= | = | 0.464 | 11.7856 |
| (4/0) 0000 |
= | = | 107.22 | 0.46 | 11.684 |
| = | = | 115 | = | 0.4527 | 11.5 |
| = | = | 110 | = | 0.4331 | 11 |
| = | (5/0) 00000 |
= | = | 0.432 | 10.9728 |
| = | = | 105 | = | 0.4134 | 10.5 |
| (3/0) 000 |
= | = | 85.01 | 0.4096 | 10.4038 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| = | (4/0) 0000 |
= | = | 0.400 | 10.16 |
| = | = | 100 | = | 0.3937 | 10 |
| = | = | 95 | = | 0.374 | 9.5 |
| = | (3/0) 000 |
= | = | 0.372 | 9.4488 |
| (2/0) 00 |
= | = | 67.43 | 0.3648 | 9.2659 |
| = | = | 90 | = | 0.3543 | 9 |
| = | (2/0) 00 |
= | = | 0.348 | 8.8392 |
| = | = | 85 | = | 0.3346 | 8.5 |
| 0 | = | = | 53.49 | 0.3249 | 8.2525 |
| = | 0 | = | = | 0.324 | 8.2296 |
| = | = | 80 | = | 0.315 | 8 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| = | 1 | = | = | 0.3 | 7.62 |
| = | = | 75 | = | 0.2963 | 7.5 |
| 1 | = | = | 42.41 | 0.2893 | 7.3482 |
| = | 2 | = | = | 0.276 | 7.0104 |
| = | = | 70 | = | 0.2756 | 7 |
| 2 | = | = | 33.62 | 0.2576 | 6.543 |
| = | = | 65 | = | 0.2559 | 6.5 |
| = | 3 | = | = | 0.252 | 6.4008 |
| = | = | 60 | = | 0.2362 | 6 |
| = | 4 | = | = | 0.232 | 5.8928 |
| 3 | = | = | = | 0.2294 | 5.8268 |
| = | = | 55 | = | 0.2165 | 5.5 |
| = | 5 | = | = | 0.212 | 5.3848 |
| 4 | = | = | 21.15 | 0.2043 | 5.1892 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| = | = | 50 | = | 0.1968 | 5 |
| = | 6 | = | = | 0.192 | 4.8768 |
| 5 | = | = | = | 0.1819 | 4.6203 |
| = | = | 45 | = | 0.1772 | 4.5 |
| = | 7 | = | = | 0.176 | 4.4704 |
| 6 | = | = | 13.3 | 0.162 | 4.1148 |
| = | 8 | = | = | 0.16 | 4.064 |
| = | = | 40 | = | 0.1575 | 4 |
| 7 | = | = | = | 0.1443 | 3.6652 |
| = | 9 | = | = | 0.144 | 3.6576 |
| = | = | 35 | = | 0.1378 | 3.5 |
| 8 | = | = | 8.3 | 0.1285 | 3.2639 |
| = | 10 | = | = | 0.128 | 3.2512 |
| = | = | 30 | = | 0.1181 | 3 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| = | 11 | = | = | 0.116 | 2.9464 |
| 9 | = | = | = | 0.1144 | 2.9058 |
| = | 12 | = | = | 0.104 | 2.6416 |
| 10 | = | = | 5.26 | 0.1019 | 2.5883 |
| = | = | 25 | 4.91 | 0.0984 | 2.5 |
| = | 13 | = | = | 0.092 | 2.3368 |
| 11 | = | = | = | 0.0907 | 2.3038 |
| 12 | = | = | 3.3 | 0.0808 | 2.0523 |
| = | 14 | = | = | 0.08 | 2.032 |
| = | = | 20 | 3.14 | 0.0787 | 2 |
| 13 | 15 | = | 2.6 | 0.072 | 1.8288 |
| 14 | = | = | 2 | 0.0641 | 1.6281 |
| = | 16 | = | = | 0.064 | 1.6256 |
| = | = | 15 | = | 0.059 | 1.5 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| 15 | = | = | = | 0.0571 | 1.4503 |
| = | 17 | = | = | 0.056 | 1.4224 |
| 16 | = | = | 1.3 | 0.0508 | 1.2903 |
| = | 18 | = | = | 0.048 | 1.2192 |
| 17 | = | = | = | 0.0453 | 1.1506 |
| 18 | = | = | 0.82 | 0.0403 | 1.0236 |
| = | 19 | 10 | 0.8 | 0.04 | 1 |
| = | 20 | = | = | 0.036 | 0.9144 |
| 19 | = | = | = | 0.0359 | 0.9119 |
| = | = | 9 | = | 0.354 | 0.9 |
| 20 | 21 | = | 0.5 | 0.032 | 0.8128 |
| = | = | 8 | 0.5 | 0.0315 | 0.8 |
| 21 | = | = | = | 0.0285 | 0.7239 |
| = | 22 | = | = | 0.028 | 0.7112 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| = | = | 7 | = | 0.0275 | 0.7 |
| 22 | = | = | 0.33 | 0.0254 | 0.6452 |
| = | 23 | = | = | 0.024 | 0.6096 |
| = | = | 6 | 0.28 | 0.0236 | 0.6 |
| 23 | = | = | = | 0.0226 | 0.5740 |
| = | 24 | = | = | 0.022 | 0.5588 |
| 24 | = | = | = | 0.0201 | 0.5105 |
| = | 25 | = | = | 0.02 | 0.508 |
| = | = | 5 | 0.2 | 0.0197 | 0.5 |
| = | 26 | = | = | 0.018 | 0.4572 |
| 25 | = | = | 0.16 | 0.0179 | 0.4547 |
| = | 27 | = | = | 0.0164 | 0.4166 |
| 26 | = | = | 0.13 | 0.0159 | 0.4039 |
| = | = | 4 | = | 0.0157 | 0.4 |
| = | 28 | = | = | 0.0148 | 0.3759 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| 27 | = | = | 0.096 | 0.0142 | 0.3607 |
| = | 29 | = | = | 0.0136 | 0.3544 |
| 28 | = | = | 0.08 | 0.0126 | 0.32 |
| = | 30 | = | = | 0.0124 | 0.315 |
| = | = | 3 | = | 0.0118 | 0.3 |
| = | 31 | = | = | 0.0116 | 0.2946 |
| 29 | = | = | = | 0.0113 | 0.287 |
| = | 32 | = | = | 0.0108 | 0.2743 |
| 30 | 33 | = | 0.049 | 0.01 | 0.254 |
| = | 34 | = | = | 0.0092 | 0.2337 |
| 31 | = | = | = | 0.0089 | 0.2261 |
| = | 35 | = | = | 0.0084 | 0.2134 |
| 32 | = | = | 0.031 | 0.008 | 0.2032 |
| = | = | 2 | = | 0.0079 | 0.2 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| = | 36 | = | = | 0.0076 | 0.193 |
| 33 | = | = | 0.026 | 0.0071 | 0.1803 |
| = | 37 | = | = | 0.0068 | 0.1727 |
| 34 | = | = | 0.02 | 0.0063 | 0.16 |
| = | 38 | = | = | 0.006 | 0.1524 |
| 35 | = | = | 0.015 | 0.0056 | 0.1422 |
| = | 39 | = | = | 0.0052 | 0.1321 |
| 36 | = | = | 0.013 | 0.005 | 0.127 |
| = | 40 | = | = | 0.0048 | 0.1219 |
| 37 | = | = | 0.0095 | 0.0045 | 0.1143 |
| = | 41 | = | = | 0.0044 | 0.1118 |
| 38 | 42 | = | 0.0078 | 0.004 | 0.1016 |
| = | = | 1 | = | 0.0039 | 0.1 |
| = | 43 | = | = | 0.0036 | 0.0914 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| 39 | = | = | 0.0064 | 0.0035 | 0.0889 |
| = | 44 | = | = | 0.0032 | 0.0813 |
| 40 | = | = | 0.0050 | 0.0031 | 0.0787 |
| 41 | 45 | = | 0.0039 | 0.0028 | 0.0711 |
| 42 | = | = | 0.0028 | 0.0025 | 0.0635 |
| = | 46 | = | = | 0.0024 | 0.0610 |
| 43 | = | = | = | 0.0022 | 0.0559 |
| 44 | 47 | = | 0.002 | 0.002 | 0.0508 |
| 45 | = | = | = | 0.00176 | 0.0447 |
| = | 48 | = | = | 0.0016 | 0.0496 |
| 46 | = | = | 0.0013 | 0.00157 | 0.0399 |
| 47 | = | = | = | 0.0014 | 0.0356 |
| 48 | 49 | = | = | 0.0012 | 0.0305 |
| AWG | SWG | Metric gauge | mm² | Diameter Inch | Diameter mm |
| 49 | = | = | = | 0.0011 | 0.0279 |
| = | 50 | = | = | 0.001 | 0.0254 |
| 50 | = | = | = | 0.00099 | 0.025146 |