Wire Gauge Calculator
Determine the correct AWG wire size based on current, distance, and acceptable voltage drop for safe and efficient solar installations.
Choosing the correct DC wire size is critical for safety and efficiency in any solar installation. Undersized wire causes excessive voltage drop, wasted energy, and can overheat. This wire gauge calculator determines the right AWG size based on your circuit's current (amps), one-way distance, system voltage, and maximum acceptable voltage drop. It handles both copper and aluminum conductors and checks NEC ampacity ratings at 75°C.
For quick reference, see the DC wire size amp rating chart below the results. Common scenarios include panel-to-combiner runs, battery-to-inverter connections, and AC subpanel feeds. Need wire for your project? Browse our wire and cables category.
Circuit Parameters
Maximum expected current
Distance from source to load
System Settings
Common scenarios:
Results
Enter your parameters to see results
Wire Sizing Fundamentals
Voltage Drop
NEC recommends keeping voltage drop under 3% for branch circuits and 5% total for the entire system. Lower voltage drop means less energy loss and better equipment performance.
Ampacity
Wire ampacity is the maximum current a conductor can carry continuously without exceeding its temperature rating. Always size for 80% of breaker rating.
Copper vs Aluminum
Copper has lower resistance and higher ampacity but costs more. Aluminum requires larger gauges but is more economical for long runs and large conductors.
Temperature Rating
This calculator uses 75°C (THHN/THWN) ratings. Higher temperature rated wire can carry more current. Always match wire rating to equipment terminals.
Need help with wiring design?
Our team can review your layout and recommend the right wire and conduit.