Wire Gauge Calculator

Determine the recommended AWG wire gauge based on current, distance, voltage, and acceptable voltage drop.

Inputs

Current

One-Way Distance

System Voltage

Max Voltage Drop

Tab to move between fields

Results

Recommended AWG

Actual Voltage Drop3.18 V

Drop Percentage2.65%

Power Loss63.5 W

Total Wire Length100 ft

How to Use This Calculator

Enter the Current (amps) the wire must carry.
Set One-Way Distance (ft) to the load.
Select System Voltage (120V or 240V).
Enter Max Voltage Drop (%) — NEC recommends 3% for branch circuits, 5% total.
Review Recommended AWG and Actual Voltage Drop to confirm the wire is adequately sized.

What each input means

Current: The current draw of the circuit in amps.
One-Way Distance: One-way wire run distance from panel to load.
System Voltage: Nominal system voltage (120V for standard, 240V for heavy appliances).
Max Voltage Drop: Maximum acceptable voltage drop percentage (NEC recommends 3%).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Current = 20, One-Way Distance = 50, System Voltage = 120, Max Voltage Drop = 3 = 4 input(s) provided
Calculate Recommended AWG
Recommended AWG
12 = 12
Calculate Actual Voltage Drop
3.18 = 3.18
Calculate Drop Percentage
Drop Percentage
2.65 = 2.65

Engine last updated July 28, 2026.

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