Voltage Drop Calculator
Estimate cable voltage drop, voltage at the load, percentage loss, conductor resistance, and power loss for DC, single-phase, or three-phase circuits.
Enter circuit details
Result
Enter the circuit and cable details to estimate voltage drop.
Longer cables drop more voltage
Conductor resistance rises with length, so longer runs create more voltage drop at the same current and cable size.
Larger conductors reduce loss
A greater cross-sectional area lowers resistance, improves load voltage, and reduces heat and wasted power.
Current has a direct effect
Voltage drop increases directly with load current. Higher-current circuits often require larger conductors.
Frequently asked questions
What voltage drop percentage is acceptable?
Many designs aim for about 3% or less on a branch circuit and about 5% or less across feeders plus branch circuits, but the correct limit depends on local codes and equipment requirements.
Why is cable length entered one way?
For DC and single-phase two-wire circuits, the calculator doubles the one-way length to include the outgoing and return conductors. Three-phase circuits use the square-root-of-three relationship.
Does temperature affect voltage drop?
Yes. Metal resistance increases as conductor temperature rises. This calculator applies an approximate temperature correction for copper or aluminium conductors.
Can this replace an electrician or electrical engineer?
No. It is a planning tool only. Final conductor size and protection must be checked against applicable electrical standards and the real installation conditions.
Results are estimates generated locally in your browser using standard electrical formulas. They are for informational and planning purposes only, not a substitute for a qualified electrician. Confirm all wiring, load and safety requirements against your local electrical code before installation. VisionVix accepts no liability for decisions based on this tool's output.
