Wire Size Calculator
Determine proper wire gauge based on amperage, distance, and voltage drop requirements
About this calculator
The Wire Size Calculator helps electricians, engineers, and DIY enthusiasts determine the correct wire gauge (AWG) for electrical installations based on current load, circuit distance, and acceptable voltage drop. Using undersized wire can cause dangerous overheating, power loss, and potential fire hazards, while oversized wire wastes money. This calculator ensures optimal wire selection for safe, efficient electrical systems by considering amperage requirements, run length, and voltage drop limits to recommend the proper conductor size.
How to use
Enter the circuit's maximum amperage (current load), the total wire run distance (one-way length from panel to load), select your system voltage, and set your acceptable voltage drop percentage (typically 3-5%). The calculator will instantly recommend the minimum required wire gauge (AWG) and show the actual voltage drop for your specific installation requirements.
Frequently asked questions
What voltage drop percentage should I use?
Most electrical codes recommend maximum 3% voltage drop for branch circuits and 5% total system voltage drop for optimal performance and efficiency.
Do I measure one-way or round-trip distance?
Measure the one-way distance from electrical panel to the load. The calculator automatically accounts for the return path in its calculations.
Can I use smaller wire if it meets ampacity ratings?
No, always use the larger gauge recommended by either ampacity or voltage drop calculations to ensure safe operation and code compliance.