Wire Gauge Converter
American Wire Gauge (AWG) is a geometric scale.
Enter Values
How to use this calculator
- Fill in exactly ONE field. To convert a gauge to metric, type the AWG number (e.g. 12); to find the nearest gauge for a metric size, type the cross-sectional area in mm².
- For gauges above 1 AWG (the '/0' sizes) use zero and negatives: 1/0 = 0, 2/0 = -1, 3/0 = -2, 4/0 = -3.
- Read the emphasised results first — the gauge name and area — then use diameter, inches and kcmil as needed.
How it works
American Wire Gauge (AWG) is a geometric scale. The bare conductor diameter for gauge n is d = 0.127 × 92^((36 − n) ÷ 39) millimetres, so each step of 6 gauges roughly halves the area and a step of 3 gauges changes the area by about 2×. The cross-sectional area follows from the circle formula, area = (π ÷ 4) × d².
To go the other way, this tool inverts the same equations: it turns your area into an equivalent diameter with d = √(4 × area ÷ π), then solves the AWG formula for n and rounds to the nearest whole gauge, since AWG only exists in discrete steps. Results also show kcmil (thousand circular mils), the North American area unit where 1 kcmil = 0.50671 mm².
Worked example
Convert 12 AWG to metric. Enter AWG gauge = 12. The converter returns a cross-sectional area of 3.309 mm², a conductor diameter of 2.0525 mm (0.08081 in), and 6.53 kcmil. This matches the common '12 AWG ≈ 3.31 mm²' figure used on cable datasheets. Working backwards, entering 3.31 mm² returns 12 AWG as the nearest standard gauge.
Common mistakes
- Confusing the '/0' gauges with positive numbers. As gauges get bigger the AWG number gets smaller, and past 1 AWG the sizes are 1/0, 2/0, 3/0, 4/0 — enter these as 0, -1, -2 and -3, not 10, 20, 30.
- Treating the AWG diameter as the cable's overall diameter. The formula gives the bare solid-conductor size; stranded conductors and insulation make the finished cable noticeably thicker.
- Assuming an exact metric area equals a standard gauge. AWG is a discrete scale, so a nominal '4 mm²' cable is close to but not identical to any single AWG size — always confirm against the manufacturer's rating.
Frequently asked questions
How do I enter big cables like 4/0 AWG?
The '/0' sizes continue below 1 AWG. Enter 1/0 as 0, 2/0 as -1, 3/0 as -2 and 4/0 as -3. The tool labels the result correctly (e.g. -3 shows as '4/0 AWG').
Why doesn't my metric size match a gauge exactly?
AWG is a fixed geometric scale, while metric cable areas (1, 1.5, 2.5, 4, 6 mm²…) are their own standard. The two rarely land on the same number, so this converter reports the nearest AWG plus that gauge's true area and the unrounded gauge for reference.
Does this size a wire for a given current?
No. It only converts between gauge, diameter and area. Ampacity depends on insulation, installation method, temperature and local wiring rules — use a dedicated cable-sizing calculator and follow your local electrical code.
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