12V Voltage DropCalculator
Calculate voltage drop for 12V DC systems including automotive, marine, RV, and solar applications. Free online calculator with NEC-compliant wire sizing.
DC Circuit Parameters
Enter your system values
Total circuit length will be 2× this value
Calculation Results
Critical - Wire size too small
12V Applications
- •Automotive electrical systems
- •Marine and boat wiring
- •RV and camper installations
- •Solar panel connections
- •LED lighting systems
- •12V battery banks
DC Formula
I = Current (A)
R = Resistance (Ω/ft)
L = One-way length (ft)
Other Calculators
12V Voltage Drop Calculation Guide
About 12V Systems
12V DC systems are widely used in automotive, marine, and small solar applications. Maintaining proper voltage at the load is critical for system performance and equipment longevity.
The NEC recommends limiting voltage drop to 3% for branch circuits and 5% total for the combination of feeder and branch circuit. For DC systems, this translates to a maximum drop of 0.4V for branch circuits.
Calculation Considerations
DC voltage drop calculations are straightforward since only resistance matters—there's no reactance to consider. The formula multiplies by 2 to account for the complete circuit (positive and negative conductors).
For 12V systems, common wire sizes range from #10 AWG for short runs to #2 AWG for high-current applications. Always verify ampacity requirements alongside voltage drop calculations.