AWG Wire Size Converter

[Please note first] This app carries no current rating: it will not tell you how many amps a wire can take. It cannot tell you whether a given wire is enough for a job either, because that depends on the ambient temperature, how many cables run together and how they are installed. Voltage drop, strand construction, insulated outside diameter and cable type codes (IV, VVF and the like) are all out of scope. It converts size figures, and nothing more. ────────── ≠ AWG Wire Size Converter — AWG 18 is not 0.75 sq You often see a table that says "AWG 18 = 0.75 sq". But AWG 18 has a cross-section of 0.8230468 mm², which is 9.739578 percent more than 0.75 mm². The number that lands exactly on 0.75 mm² is AWG 18.4008, and that is not a whole number. That table is somebody's rounding. ■ How it works Convert between the AWG number, the diameter in mm and the cross-section in mm², in any direction. All three appear together on one line under the answer, so you never have to look the third one up again. The nine Japanese nominal sizes sit in the presets. ■ The same 2.005032 turns up twice Six numbers apart, the diameter changes by a factor of 2.005032. Three numbers apart, the cross-section changes by the same 2.005032. Area goes as the square of the diameter, so the ratio that takes six gauges in diameter takes only three in cross-section. You hear both "six gauges doubles it" and "three gauges doubles it", and the two are talking about different quantities. Six numbers apart, the cross-section is 4.020151 times over, not two. ■ AWG and the Japanese nominal sizes do not line up AWG runs in a constant ratio, while the Japanese nominal sizes (0.75, 1.25, 2.0 and so on) are fixed values written into a standard. The two were settled separately, so the gap between them never settles either. Across the nine nominal sizes the difference from the nearest whole gauge runs from 9.739578 percent above to 5.463632 percent below: five above, four below. Neither ladder is wrong. Two that were built separately simply stand near each other. ■ How AWG is defined The anchor is AWG 36, whose diameter is exactly 0.127 mm. Going 39 numbers down multiplies the diameter by 92, and every number in between is filled in at a constant ratio. AWG 0 comes out at 8.251463 mm. The cross-section is worked as a plain circle: pi divided by four, times the diameter squared. ■ The table inside the app (AWG 4 to 30, even numbers) AWG 4 … 5.189396 mm, 21.15064 mm² AWG 10 … 2.588187 mm, 5.261155 mm² AWG 18 … 1.023687 mm, 0.8230468 mm² AWG 24 … 0.5105592 mm, 0.2047303 mm² AWG 30 … 0.254639 mm, 0.05092602 mm² ■ Good for ▪ An imported cable or part marked only with an AWG number ▪ Working out roughly what "sq" a wire in your hand would be called ▪ Remembering which of the two claims about doubling belongs where ▪ Checking how far a printed conversion table can be trusted ■ Things worth knowing (included in the app) ▪ AWG 18 is 0.8230468 mm², not 0.75 sq ▪ One figure, 2.005032, covers six gauges of diameter and three of area ▪ AWG and the Japanese nominal sizes drift by a different amount each time ▪ The anchor is AWG 36 at exactly 0.127 mm; 39 numbers multiply it by 92 ▪ "0.75 sq" just means 0.75 mm². It is not a separate unit ■ How the app is built ▪ A single screen. No settings page, no tabs to hunt through ▪ The table runs AWG 4 to 30 in even numbers, diameter beside cross-section ▪ Your last five entries are kept and can be tapped to restore ▪ Japanese and English, following your device language ▪ No account needed. The conversion runs on your device and your figures are never sent anywhere ────────── Note: every figure on screen is rounded to seven significant digits, while the ratios and percentages above are worked from the unrounded formula, so dividing two rows of the table can leave the last digit one off. This app carries no current rating, and it cannot tell you whether a given wire is enough for a job.