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ElecToolsHQ

Voltage Drop Calculator

Calculate voltage drop from current and total conductor resistance (VD = I × R).

Total round-trip resistance of the conductor run.

Formula

VD = I × R

VD
Voltage drop, in volts
I
Current, in amps
R
Total conductor resistance, in ohms

What this calculator does

Calculates the voltage lost across a conductor run from current and total resistance.

Use cases

  • Check expected voltage drop on a circuit run before installation
  • Verify a measured voltage drop against the expected calculation
  • Compare two conductor sizes by their resulting voltage drop

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