Determine the correct wire gauge (AWG) for your electrical circuit. Enter the amperage, one-way wire run distance, and voltage to calculate the recommended wire size that keeps voltage drop within acceptable limits. Proper wire sizing is critical for safety and code compliance.
Enter Your Measurements
Results
Recommended Wire Size
10
AWG
Wire Ampacity
30
amps
Voltage Drop
3.11
volts
Voltage Drop
2.59
%
Formula
How to Use This Calculator
How to Use
- 1
Enter the circuit amperage (check breaker size or appliance nameplate).
- 2
Enter the one-way distance from the panel to the load in feet.
- 3
Enter the circuit voltage (120V for standard circuits, 240V for large appliances).
- 4
Set the maximum voltage drop (3% is recommended, 5% is acceptable for branch circuits).
Frequently Asked Questions
Frequently Asked Questions
What size wire for a 20-amp circuit?
What happens if wire is too small?
Should I use copper or aluminum wire?
In-Depth Guides
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About This Calculator
This calculator uses the formula: Circular Mils = (2 × 10.75 × Amps × Distance) ÷ Max Voltage Drop | Select AWG with sufficient circular mils and ampacity. All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.
Built and maintained by the CalcSmart team. Last updated March 2026.
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