AWG Wire Size Calculator: Diameter, mm² & Inches

Calculation formulas

d(mm) = 0.127 × 92^((36 − n)/39) · A(mm²) = πd²/4 · n = 36 − 39 log(d/0.127)/log(92)

A larger AWG number means a smaller conductor

AWG follows a geometric progression: 36 AWG is 0.005 inch and 4/0 AWG is 0.46 inch, separated by 39 steps. This tool calculates from that definition, so displayed precision may exceed a rounded manufacturer table. Gauges 0, 00, 000 and 0000 are written as 1/0, 2/0, 3/0 and 4/0.

Nearest gauge or not-smaller gauge?

Inverse conversion usually gives a fractional gauge. Nearest rounds that continuous AWG number; not-smaller selects toward a thicker conductor. For example, 1 mm² is closest to 17 AWG, whose nominal area is about 1.038 mm². When a minimum area is required, use the separate not-smaller result rather than rounding blindly.

Can I use the outside diameter of stranded wire?

No. Stranding adds voids and insulation adds more diameter. If each strand diameter is known, sum the circular metal areas before converting the total area to equivalent AWG. Confirm the actual product against its manufacturer specification.

Why is no maximum current listed?

Allowable current depends on material, insulation temperature, ambient conditions, installation, bundling and the applicable rules. Geometry conversion is not cable selection; use the related tools for voltage-drop estimates.

Size and code reference

Related tools

Formula and data references

• NBS Handbook 100: Copper Wire Tables
• Alpha Wire / Belden: Conductor Chart