Copper conductor ampacity per NEC Table 310.16, breaker sizing limits, AWG to mm² cross-reference, and a quick circuit guide. Print it or save as PDF for the workshop wall.
| AWG size | 60 °C (TW) | 75 °C (THW / THWN) | 90 °C (THHN / XHHW-2) | mm² (approx) |
|---|---|---|---|---|
| 14 | 15 A | 20 A | 25 A | 2.1 |
| 12 | 20 A | 25 A | 30 A | 3.3 |
| 10 | 30 A | 35 A | 40 A | 5.3 |
| 8 | 40 A | 50 A | 55 A | 8.4 |
| 6 | 55 A | 65 A | 75 A | 13.3 |
| 4 | 70 A | 85 A | 95 A | 21.2 |
| 3 | 85 A | 100 A | 115 A | 26.7 |
| 2 | 95 A | 115 A | 130 A | 33.6 |
| 1 | 110 A | 130 A | 145 A | 42.4 |
| 1/0 | 125 A | 150 A | 170 A | 53.5 |
| 2/0 | 145 A | 175 A | 195 A | 67.4 |
| 3/0 | 165 A | 200 A | 225 A | 85.0 |
| 4/0 | 195 A | 230 A | 260 A | 107 |
Use the temperature column that matches the lowest-rated termination in the circuit. Most breakers and lugs are rated 75 °C, so the 75 °C column governs for typical residential and commercial work even when the wire insulation is rated 90 °C.
Aluminium carries roughly 78 percent of the same-size copper ampacity, so it is sized one to two AWG larger for the same load. Common 75 °C aluminium values: 8 AWG = 40 A, 6 AWG = 50 A, 4 AWG = 65 A, 2 AWG = 90 A, 1/0 = 120 A, 2/0 = 135 A, 4/0 = 180 A. For a full aluminium calculation, use the wire gauge calculator.
| AWG | Exact mm² | Nearest metric size | Typical use |
|---|---|---|---|
| 16 | 1.31 | 1.5 mm² | Lighting circuits, control wiring |
| 14 | 2.08 | 2.5 mm² | 15 A circuits, general outlets (US) |
| 12 | 3.31 | 4 mm² | 20 A outlets, kitchen and bathroom |
| 10 | 5.26 | 6 mm² | 30 A circuits, EV charger 7.4 kW |
| 8 | 8.37 | 10 mm² | 40 A circuits, EV charger 11 kW, ranges |
| 6 | 13.3 | 16 mm² | 55 A circuits, sub-panel feeds |
| 4 | 21.2 | 25 mm² | Sub-panels, large appliance feeds |
| 2 | 33.6 | 35 mm² | Service and feeder runs |
| 1/0 | 53.5 | 50 mm² | Main supply, generator feed |
| Circuit / load | Breaker | Minimum copper wire |
|---|---|---|
| Lighting, general 120 V | 15 A | 14 AWG |
| Outlets, kitchen, 120 V | 20 A | 12 AWG |
| Water heater, dryer feed | 30 A | 10 AWG |
| EV charger, 7.4 kW continuous | 40 A | 8 AWG |
| Electric range, 11 kW | 50 A | 6 AWG |
| Sub-panel feed, 100 A | 100 A | 3 AWG |
Continuous loads (EV chargers, motors, heaters running 3 hours or more) must be sized at 125 percent of the running current before reading the ampacity table. The values above already include that allowance.