Wire Gauge Calculator
Convert between AWG and cross-sectional area, and check ampacity.
About Wire Gauge Calculator
AWG is a logarithmic scale: every six gauges roughly doubles the diameter and every three gauges doubles the area. The ampacity shown is an approximation for insulated copper in free air and must be derated for grouping and ambient temperature. Because the scale runs backwards, mistaking 10 AWG for 1/0 AWG understates conductor area by a factor of ten.
Formula
Wire Gauge
Diameter (mm) = 0.127 × 92^((36 − AWG) ÷ 39); area = π (d ÷ 2)²
- AWG
- American Wire Gauge, where a smaller number means a larger conductor
Worked example
With the default values below, Wire Gauge Calculator returns Cross-Sectional Area of 5.2612. Change any input above and every figure here is recalculated in your browser.
Inputs used
- AWG sizeaccepts -3–40
- 10
- Current to carryminimum 0 A
- 30 A
- Run lengthminimum 0 m
- 20 m
Results
- Cross-Sectional Area
- 5.2612 mm2
- Conductor Diameter
- 2.5882 mm
- Approximate Ampacity in Free Air
- 23.7 A
- Current Density at That Load
- 5.702 A/mm2
- Resistance of the Run
- 0.06554 ohm
Step by step
- 1Values used
- 2Wire Gauge
- 3Cross-Sectional Area= 5.2612 mm2
- 4Conductor Diameter= 2.5882 mm
- 5Approximate Ampacity in Free Air= 23.7 A
- 6Current Density at That Load= 5.702 A/mm2
- 7Resistance of the Run= 0.06554 ohm
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Wire Gauge calculated?
Diameter (mm) = 0.127 × 92^((36 − AWG) ÷ 39); area = π (d ÷ 2)² AWG is a logarithmic scale: every six gauges roughly doubles the diameter and every three gauges doubles the area. The ampacity shown is an approximation for insulated copper in free air and must be derated for grouping and ambient temperature.
Why does Wire Gauge matter?
Because the scale runs backwards, mistaking 10 AWG for 1/0 AWG understates conductor area by a factor of ten.
What values do I need to enter?
This calculator takes 3 inputs: AWG size, Current to carry, Run length. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.