Voltage Drop Calculator

Estimates the magnitude of voltage loss along a resistive path using Ohm’s law. You can enter a total loop resistance directly, or build it from conductor length, cross-section, copper/aluminum resistivity with a linear temperature correction, and the number of identical series segments (for example two for a go-and-return run).

Free · No limits · Runs in your browser

How to use

  1. 1Choose whether you know total loop resistance or want to compute it from geometry.
  2. 2Enter load current in amperes.
  3. 3Either enter resistance in ohms, or enter one-way length, cross-section in mm², material, temperature, and how many identical conductors are in series.
  4. 4Read voltage drop in volts.

Frequently asked questions

Is this valid for AC?
It is a resistive (DC-equivalent) magnitude model. Real AC feeders need impedance (R + jX) and power factor context for accurate drop.
Does it replace code ampacity tables?
No. It does not size conductors or apply NEC/IEC rules.

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