Enter the American Wire Gauge (AWG) value and select the output unit to determine the approximate wire diameter in millimeters and/or inches.

Gauge to Diameter Converter

Enter an AWG gauge value to calculate the approximate wire diameter.

Valid range: 0 to 40 AWG. The converter uses the standard AWG geometric progression formula.

Gauge to Diameter Formula

The American Wire Gauge system defines wire diameter on a logarithmic scale. The following formulas are used to convert a gauge value into its approximate diameter in millimeters or inches.

d_{mm} \approx 0.127 \times 92^{(36 - G)/39}
d_{in} \approx 0.005 \times 92^{(36 - G)/39}

Variables:

  • dmm is the wire diameter in millimeters
  • din is the wire diameter in inches
  • G is the American Wire Gauge (AWG) number

To calculate the wire diameter, substitute the gauge number into the formula. A smaller AWG value produces a larger diameter, while a larger AWG value produces a smaller diameter.

Because the AWG scale is geometric, equal changes in gauge create the same percentage change in diameter. Each step changes diameter by a factor of 921/39, and 36 AWG is defined as 0.127 mm (0.005 in).

What is Gauge to Diameter Conversion?

Gauge to diameter conversion is the process of turning an American Wire Gauge number into a physical wire size. In the AWG system, a smaller gauge number means a thicker wire, which is the opposite of how direct measurements such as millimeters or inches work.

This conversion is useful when selecting conductors, comparing wire sizes, checking manufacturer data, or planning layouts where the actual diameter matters more than the gauge label. Using the standard AWG formula lets you quickly find the corresponding wire diameter without looking up a large reference table.

How to Calculate Gauge to Diameter?

The following steps outline how to calculate the wire diameter from a gauge value.

  1. First, determine the American Wire Gauge value G.
  2. Next, choose whether you want the diameter in millimeters or inches.
  3. Substitute the gauge value into the appropriate formula: d(mm) ≈ 0.127 × 92(36 − G)/39 or d(in) ≈ 0.005 × 92(36 − G)/39.
  4. Evaluate the expression to find the approximate wire diameter.
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following example to test your understanding of the conversion.

Gauge (G) = 12

Diameter = 2.053 mm = 0.0808 in

Gauge to Diameter Conversion Table

The table below shows approximate diameters for several common AWG sizes using the standard formulas above.

Gauge (AWG) Diameter (mm) Diameter (in)
8 3.264 mm 0.1285 in
10 2.588 mm 0.1019 in
12 2.053 mm 0.0808 in
14 1.628 mm 0.0641 in
16 1.291 mm 0.0508 in
18 1.024 mm 0.0403 in
20 0.813 mm 0.0320 in

In practice, published AWG tables may show slightly different rounding, but they are all based on the same logarithmic definition. Understanding the formula makes it easier to estimate wire size and compare gauge values with real-world measurements.