What this converter does
This converter turns a wire diameter in millimetres into its AWG gauge and back. Because AWG is geometric, the gauge number falls as the diameter rises — and a fixed millimetre change does not equal a fixed gauge change. Enter a diameter and read the nearest gauge instantly.
Use it to match a metric conductor spec to an American gauge. The result can be fractional; round to the nearest standard gauge in practice.
The units it covers
American Wire Gauge is a geometric scale — each gauge step changes the diameter by a fixed ratio, so the relationship to millimetres is not a straight factor.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Wire gauge | AWG | n | Lower number = thicker wire |
| Diameter | mm | d | Bare conductor diameter |
The formula
Each AWG step multiplies the diameter by the 39th root of 92, so the conversion is exponential rather than a fixed ratio:
d(mm) = 0.127 × 92^((36 − AWG) ÷ 39)Where:
- AWG = the gauge number (can be 0, 00, 000…)
- d = bare conductor diameter in millimetres
- 0.127 = diameter of 36 AWG in mm
Worked example
Find the AWG gauge of a 2.05 mm diameter wire.
AWG = 36 − 39 × log(d ÷ 0.127) ÷ log(92)36 − 39 × log(16.14) ÷ log(92) ≈ 12So 2.05 mm is about 12 AWG — round a fractional result to the nearest gauge.
The units in this example
The bare conductor diameter in millimetres, the way metric cable is specified.
- 2.05 mm ≈ 12 AWG
- 1.63 mm ≈ 14 AWG
- 0.81 mm ≈ 20 AWG
- 8.25 mm ≈ 0 AWG
The nearest American Wire Gauge. Standard sizes are whole numbers, so round the converter output in practice.
- 12 AWG ≈ 2.05 mm
- 18 AWG ≈ 1.0 mm
- 10 AWG ≈ 2.59 mm
- AWG = 36 − 39·log(d/0.127)/log(92)