This calculator converts an American Wire Gauge number into the physical dimensions of the wire: its diameter and its cross-sectional area, in both metric and imperial units. American Wire Gauge, or AWG, is a standardised system for specifying the thickness of round electrical wire, widely used for cables, electronics and motor windings. Its scale runs counter to intuition: the larger the gauge number, the thinner the wire. This comes from the manufacturing history, where the number counted the drawing operations needed to reduce the wire, so a 30 gauge wire is fine and delicate while a 4 gauge wire is thick and heavy. Each step in gauge changes the diameter by a fixed ratio, and every six gauges roughly halves or doubles the diameter, with the area, which determines current capacity, changing even faster. Because the relationship is a precise geometric formula rather than a simple table, converting a gauge to a real dimension is awkward to do in your head. This tool does it exactly. You enter the AWG number and it returns the wire's diameter in millimetres and inches, and its cross-sectional area in square millimetres and in circular mils, the traditional unit for wire area. The cross-sectional area is the figure that really matters for electrical work, since it governs how much current a wire can safely carry and how much resistance it has. The results update as you type. Use it to interpret a wire specification, to compare gauges, or to find the metric equivalent of an AWG size when working with components specified in different systems. The formula follows the AWG standard and the results are rounded for display.
AWG: a higher number means a thinner wire. Diameter (mm) = 0.127 x 92 ^ ((36 - n) / 39). Cross-section governs current capacity. Rounded for display.
The wire diameter in millimetres is 0.127 multiplied by 92 raised to the power of 36 minus the gauge number, all divided by 39. This standard formula means each gauge step changes the diameter by a fixed ratio. The cross-sectional area is pi times the radius squared, which determines the wire's current capacity and resistance.
For 12 gauge wire, the diameter is 0.127 times 92 to the power of 36 minus 12, divided by 39, which works out to about 2.053 millimetres, or 0.0808 inches. Its cross-sectional area is about 3.31 square millimetres, equivalent to about 6.53 thousand circular mils, a common size for general wiring.
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