What this converter does
This converter turns an AWG wire gauge into its diameter in millimetres and back. AWG is a geometric scale, so a lower gauge number means a thicker wire — and each step is a fixed ratio, not a fixed millimetre difference. Type a gauge and read the diameter instantly.
Use it to match American gauge sizes to metric cable specs. For 0, 00 and 000, enter −1, −2 and −3 as the gauge number.
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 diameter of 12 AWG wire in millimetres.
d = 0.127 × 92^((36 − 12) ÷ 39)0.127 × 92^0.615 = 2.053 mmSo 12 AWG is about 2.05 mm in diameter — a common house-wiring size.
The units in this example
The American Wire Gauge number. Lower numbers are thicker; every 6 gauges roughly doubles or halves the diameter.
- 12 AWG ≈ 2.05 mm
- 14 AWG ≈ 1.63 mm
- 20 AWG ≈ 0.81 mm
- 0 AWG ≈ 8.25 mm
The bare conductor diameter. Cross-sectional area (mm²) is often quoted too — it scales with the diameter squared.
- 2.05 mm ≈ 12 AWG
- 1.63 mm ≈ 14 AWG
- 1.0 mm ≈ 18 AWG
- d = 0.127 × 92^((36−AWG)/39)