The Wire Gauge (AWG) Calculator converts between wire diameter, cross-sectional area and the American Wire Gauge (AWG) number, and can also pick the smallest standard wire that meets a required ampacity. It works for both copper and aluminum conductors using NEC 310.16 ampacity tables.
Wire Gauge (AWG) Calculator
Find the right AWG wire size from conductor diameter, cross-sectional area, or required ampacity. Includes copper and aluminum ampacity (NEC 310.16).
Input
Result
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AWG size
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amp @75C Cu
About Wire Gauge (AWG) Calculator
Features
- Find AWG from a measured diameter (mm or inches)
- Find AWG from cross-sectional area (mm2, circular mils)
- Pick the smallest AWG for a required ampacity
- Copper and aluminum ampacity at 60/75/90C
- Diameter, area, resistance and ampacity in one report
How to Use
- Choose an input mode: Diameter, Area, or Ampacity.
- Enter the value and select units.
- Read the nearest AWG and its diameter, area and ampacity.
- Copy or download the report.
Examples
Example: Enter diameter 2.05 mm to get 12 AWG (3.31 mm2, 25A at 75C copper).
Benefits
- Quickly identify unknown wires
- Confirm a wire is large enough for the load
- Compare copper vs aluminum sizing
Frequently Asked Questions
What does AWG mean?
AWG (American Wire Gauge) is the standard US wire sizing system. A smaller number means a thicker wire; 4/0 is the thickest common size.
How do I find AWG from diameter?
Use Diameter mode. Enter the measured diameter in mm or inches and the tool returns the nearest standard AWG plus its area and ampacity.
What ampacity can an AWG carry?
Per NEC 310.16 at 75C: 14AWG=20A, 12AWG=25A, 10AWG=35A, 8AWG=50A, 6AWG=65A, 4AWG=85A, 2AWG=115A, 1/0=150A, 4/0=230A (copper).
Does aluminum need a bigger size?
Yes. Aluminum has about 61% of copper conductivity, so it needs roughly two AWG sizes larger for the same ampacity.
Is my data saved?
No. All calculations run in your browser and nothing is uploaded or stored.