Choose the correct AWG or mm² wire size for your DC circuit. Enter current, length, system voltage, and acceptable voltage drop to get a precise recommendation with resistance and power-loss figures.
Total conductor path is 2× this value (out and back).
Affects max ampacity derating per gauge.
| AWG | mm² | Ω / km | V-Drop (V) | V-Drop (%) | Max Amps | Status |
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Ampacity values are approximate (NEC / PRC-005-1 chassis or typical power transmission ratings at 60–75 °C). Always verify against local code, temperature, and bundling factors.
The right wire gauge depends on your current draw, cable length, and acceptable voltage drop. A common rule for 12V DC solar systems is to keep voltage drop under 3%. For example, a 10A load 5 meters away typically needs 10 AWG (5.26 mm²) copper wire, while higher currents or longer runs may require 8 AWG or 6 AWG.
Voltage drop increases linearly with wire length because longer wires have more resistance. In DC circuits, the total conductor length is twice the one-way distance (out and back), so voltage drop equals 2 × length × current × resistivity ÷ cross-sectional area. Doubling the wire length doubles the voltage drop unless you increase the wire gauge.
AWG (American Wire Gauge) is the North American standard, where a smaller number means a thicker wire (e.g., 10 AWG is thicker than 14 AWG). mm² measures the cross-sectional area directly and is used in metric countries. 10 AWG equals approximately 5.26 mm², 12 AWG is about 3.31 mm², and 14 AWG is around 2.08 mm². Use the calculator above to convert between them instantly.