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AWG to mm² Wire Size Converter

Enter a wire gauge or area and choose a conversion direction.

How it is calculated

Choose a direction, then enter one number. From AWG to area the tool uses A = 0.012668 × 92(36 − AWG) / 19.5, where A is the conductor cross-section in mm². From area to AWG it inverts this: AWG = 36 − 19.5 × ln(A / 0.012668) / ln(92). The conductor diameter is then d = √(4A / π) in mm, which treats the wire as a solid round conductor. The AWG figure is shown with one decimal and areas and diameters with four. The area given in mm² must be greater than zero. An AWG entry is not limited, so values of 0 or below also compute. The result is the geometric size only, not a current rating.

Worked example

Convert 12 AWG to area. The exponent is (36 − 12) / 19.5 = 1.2308. Then 92 to that power is about 261.2, and multiplying by 0.012668 gives 3.3089. The tool shows 3.3089 mm². The diameter is √(4 × 3.3089 / π) = 2.0526 mm. Run the other direction with 2.5 mm² and the tool gives 13.2 AWG, with a diameter of 1.7841 mm. That is between 13 and 14 AWG, so you would pick a nearby real size.

Try this example →

Common mistakes

  • Leaving the direction on AWG to mm² when typing an area. 2.5 would be read as gauge 2.5 and give about 29.95 mm².
  • Assuming a bigger AWG number is a bigger wire. It is the opposite: 12 AWG is thicker than 20 AWG.
  • Using the result as the wire's current rating. The tool gives only geometry; ampacity depends on insulation, temperature and installation.
  • Treating the AWG result in the mm² to AWG direction (for example 13.2) as an orderable size. Real gauges are whole numbers, so round to a standard neighbour and check which side is safer.
  • Applying the result to stranded wire. The diameter assumes one solid round conductor, so a stranded cable of the same copper area is somewhat thicker overall.

About this calculator

American Wire Gauge (AWG) is the sizing standard used across North America for round, solid, non-ferrous conductor wire, while most of the rest of the world specifies wire by its cross-sectional area in square millimeters — a mismatch that trips up anyone sourcing parts, reading a datasheet, or wiring equipment across regions. AWG size follows a geometric progression where the diameter in inches is d = 0.005 × 92^((36−n)/39) for gauge n, so each drop of 3 gauge numbers roughly doubles the cross-sectional area (and every 6-gauge drop doubles the diameter).

This calculator converts a given AWG size to its equivalent area in mm² (or the reverse), and also reports the conductor diameter, using the standard AWG-to-metric relationship — the same reference electricians, cable manufacturers, and hobbyists use to match a European mm² cable spec to its closest AWG equivalent, or to check a wire’s current-carrying capacity against ampacity tables that are published in one unit or the other.

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Comments (1)

  • Editorial team

    The big sizes are written 1/0, 2/0, 3/0 and 4/0, and there is no slash key to type here. Enter them as 0, -1, -2 and -3 instead: -3 gives 107.22 mm², which is the 4/0 conductor. The result then reads as a negative AWG number, so match it back to the slash notation yourself. As a sanity check, 12 AWG is 3.31 mm² and 9 AWG is 6.63 mm². Which sizes do you convert most often?

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