Professional calculator for 12 volt DC systems. Perfect for automotive, RV, marine, and solar panel installations.
Use our full calculator with charts, PDF export, and project management.
Open Full CalculatorCar and truck electrical systems typically operate at 12V. Proper wire sizing is critical for headlights, audio systems, winches, and aftermarket accessories.
RV house batteries run at 12V DC. Long wire runs from batteries to appliances require careful voltage drop calculations.
Boats use 12V systems for navigation lights, bilge pumps, and electronics. Salt water environments require extra attention to wire sizing and connections.
Small solar installations often use 12V battery banks. Wire sizing between panels, charge controller, and batteries is essential for efficiency.
Recommended wire sizes for 3% voltage drop at 12V DC:
| Current (A) | 10 ft | 25 ft | 50 ft | 100 ft |
|---|---|---|---|---|
| 5A | 18 AWG | 16 AWG | 14 AWG | 10 AWG |
| 10A | 16 AWG | 14 AWG | 10 AWG | 8 AWG |
| 20A | 14 AWG | 10 AWG | 8 AWG | 6 AWG |
| 30A | 12 AWG | 8 AWG | 6 AWG | 4 AWG |
| 50A | 10 AWG | 6 AWG | 4 AWG | 2 AWG |