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Wire Gauge (AWG) Converter
Convert American Wire Gauge sizes to diameter in millimeters, cross-sectional area, estimated free-air ampacity, and run-length resistance, entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Range −4 (0000) to 40
Example shown — replace it with your own gauge and run length.
How the Wire Gauge Converter works
- Enter an AWG size (American Wire Gauge), from 0000 (-4) down to 40.
- Optionally set a strand count for bundled/stranded wire and a one-way run length in meters.
- The tool computes diameter, cross-sectional area, an estimated ampacity, and resistance instantly.
The formula
AWG diameter follows a 921/39 geometric progression: each 6-gauge step roughly halves or doubles the wire's cross-sectional area. Resistance is estimated from copper's resistivity (about 17.2 Ω·mm²/km) divided by the total cross-sectional area of the bundle.
FAQ
How is AWG converted to millimeters?
The American Wire Gauge system uses a logarithmic formula: diameter in inches = 0.005 × 92^((36 − AWG) / 39). This tool converts that to millimeters and derives cross-sectional area and resistance from it.
Is the ampacity figure exact?
No — it is a rough free-air copper ampacity estimate for common gauges, meant to give you a ballpark. Real ampacity depends on insulation type, bundling, ambient temperature, and the applicable electrical code, so always check NEC/IEC tables or a licensed electrician for anything safety-critical.
What does "round-trip resistance" mean?
It is the resistance of the wire over the one-way run length you enter, doubled to account for both the outgoing and return conductors — useful for estimating voltage drop on a DC circuit like a car audio or solar install.
How we compare
| Feature | Online Tool Store | Printed AWG chart | Electrician's app |
|---|---|---|---|
| Instant recalculation | ✓ | ✗ | ✓ |
| Run-length voltage-drop resistance | ✓ | ✗ | ✓ |
| Code-certified ampacity ratings | ✗ | ✓ | ✓ |
Use this for quick estimates and hobby projects; use an official NEC/IEC ampacity table for any circuit where safety margins matter.