Voltage Drop Calculator
Calculate voltage drop in electrical circuits
About this calculator
A voltage drop calculator determines the reduction in electrical voltage that occurs when current flows through wire resistance in electrical circuits. This tool is essential for electricians, engineers, and DIY enthusiasts to ensure proper wire sizing and maintain adequate voltage levels at load points. Calculating voltage drop helps prevent equipment malfunction, power losses, and ensures electrical systems operate safely and efficiently within acceptable voltage tolerances.
How to use
Enter the circuit current in amperes, wire length (one-way distance), conductor material type, and wire gauge size. The calculator will compute the voltage drop and percentage drop based on your system voltage. Compare results against code requirements (typically 3% for branch circuits, 5% total) to verify proper wire sizing.
Frequently asked questions
What is acceptable voltage drop percentage?
Most electrical codes allow maximum 3% voltage drop for branch circuits and 5% total from service panel to final load point.
Does wire length mean round-trip distance?
No, enter one-way distance. The calculator automatically accounts for the complete circuit path including return conductor in its calculations.
How does wire material affect voltage drop?
Copper has lower resistance than aluminum, resulting in less voltage drop. Aluminum requires larger wire sizes to achieve equivalent performance.