Wire Size Calculator
Calculate the proper wire gauge for electrical circuits based on current, distance, and voltage drop
About this calculator
This wire size calculator helps electricians, contractors, and DIY enthusiasts determine the proper wire gauge (AWG) for electrical circuits to ensure safety and code compliance. By calculating wire size based on current load, circuit distance, and acceptable voltage drop, it prevents overheating, power loss, and potential fire hazards. Proper wire sizing is crucial for electrical system efficiency and meeting National Electrical Code requirements.
How to use
Enter your circuit's current draw in amperes, the total distance the wire will run (round trip), and your acceptable voltage drop percentage (typically 3-5%). Select your voltage type (120V, 240V, etc.) and the calculator will recommend the minimum wire gauge needed to safely carry the load while maintaining voltage within acceptable limits.
Frequently asked questions
What voltage drop percentage should I use?
The NEC recommends maximum 3% voltage drop for branch circuits and 5% total for feeders and branch circuits combined.
Should I measure one-way or round-trip distance?
Always use the round-trip distance since electricity travels through both hot and neutral wires, doubling the actual wire length.
Can I use a smaller wire gauge than recommended?
Never use smaller wire than calculated, as this creates safety hazards. You can use larger wire for future capacity or longer runs.