Voltage Drop Calculator

Change any input to update the calculation. Unit changes preserve the physical quantity.

CALCULATION SETUP

Inputs

Need an input value?
V

For three-phase, enter line-to-line voltage.

Need an input value?
A
Need an input value?
Motor Current Estimate Reference ↗Conditional motor estimate only; verify nameplate current and protection separately.
Need an input value?
Wire Resistance Chart ↗Bulk resistance only; ampacity and installation checks remain separate.
Need an input value?
Wire Resistance Chart ↗Bulk resistance only; ampacity and installation checks remain separate.
mm²
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Conductor temperature, not ambient air; converted limits are −40 to 150 °C.

Need an input value?
Wire Resistance Chart ↗Bulk resistance only; ampacity and installation checks remain separate.
%

Planning criterion only; this value is not a code-compliance threshold.

Calculated locally in your browser. No sign-up or input upload.

CALCULATED VALUE

Results

Approximate voltage drop

2.759 V

Voltage drop

11.494 %

Approximate load voltage

21.241 V

One-way conductor resistance

0.13793 Ω

Approximate conductor power loss

27.586 W

Conductor cross-sectional area

2.5 mm²

One-way cable length

20 m65.617 ft
SupplyLoadOne-way 20 mΔV 2.759 V · Rone 0.138 Ω
One-way cable route between supply and load · schematic, not to scale

Calculation breakdown

Entered conductor
2.5 mm²
Model
Two-conductor DC resistive loop

Only the result summary and canonical link are shared. Inputs and free-form names are excluded.

Assumptions & checks

Wire sizing here is based on the voltage-drop criterion only. It does NOT establish ampacity, installation method, temperature derating or local electrical-code compliance.

Drop exceeds 3%. Compare with your chosen target and installation requirements; 3% is not a compliance verdict.

Calculated voltage drop exceeds your entered target.