Wire Gauge Chart: AWG to Millimeters and Inches
Convert American Wire Gauge (AWG) sizes to diameter in millimeters and inches, with common uses for each gauge size.
Diameter (mm): 8.25
| AWG | Diameter (mm) | Diameter (in) | Common Use |
|---|---|---|---|
| 0 | 8.25 | 0.3249 | Heavy power distribution |
| 4 | 5.19 | 0.2043 | Service entrance wiring |
| 6 | 4.12 | 0.162 | Subpanel feeders, large appliances |
| 8 | 3.26 | 0.1285 | Electric ranges, large appliances |
| 10 | 2.59 | 0.1019 | Dryers, water heaters |
| 12 | 2.05 | 0.0808 | Standard household outlets (20A) |
| 14 | 1.63 | 0.0641 | Lighting circuits (15A) |
| 16 | 1.29 | 0.0508 | Extension cords, low-voltage |
| 18 | 1.02 | 0.0403 | Lamp cords, thermostats |
| 20 | 0.81 | 0.032 | Automotive wiring, electronics |
| 22 | 0.64 | 0.0253 | Signal wiring, breadboarding |
| 24 | 0.51 | 0.0201 | Telephone, low-current signals |
How to Measure
If you have a length of wire and need to identify its gauge, measure its diameter (excluding insulation) with calipers in millimeters or inches and match it to the closest value in this table. Note that smaller AWG numbers indicate thicker wire — the scale runs in the opposite direction from most size systems.
Notes
AWG follows a geometric progression: each step of 3 gauge numbers roughly doubles or halves the wire's cross-sectional area, which is why the diameter values don't decrease by a constant amount between rows. Wire gauge selection for electrical work should always follow local electrical code requirements based on the circuit's amperage, not just the gauge-to-diameter conversion alone.
Frequently Asked Questions
Source: American Wire Gauge (AWG) standard, ASTM B258 · see our methodology