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Voltage Drop Calculator

Estimate voltage drop and percentage loss in a cable run.

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Enter current, one-way length, conductor size and material.

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Assumptions and limits.
  • Copper conductor at 20 °C unless another temperature is entered; two-wire run unless chassis return is selected.

Voltage drop

For a two-wire run, V_drop = 2 × I × ρ × L / A. The result is an estimate for the stated conductor temperature.

Frequently asked questions

What voltage drop is acceptable?
Acceptable drop depends on the application and standard. This tool reports the value; it does not certify a design.
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