About this calculator

Voltage drop = 2 × L × I × ρ / A for single-phase circuits. ρ (copper) ≈ 0.0175 Ω·mm²/m, (aluminium) ≈ 0.028. Aim to keep total drop under 3% for lighting, 5% for power.

Formula: Vd = 2 × L × I × ρ / A

Frequently asked questions

What does the Voltage Drop Calculator do?

Estimate voltage drop along a copper or aluminium cable run for any load. Voltage drop = 2 × L × I × ρ / A for single-phase circuits. ρ (copper) ≈ 0.0175 Ω·mm²/m, (aluminium) ≈ 0.028. Aim to keep total drop under 3% for lighting, 5% for power.

Is the Voltage Drop Calculator free to use?

Yes. Every calculator on Calcora is free, works in your browser without sign-up, and can be embedded on your own website.

How accurate is the Voltage Drop Calculator?

Results are calculated in real time using the formula Vd = 2 × L × I × ρ / A. Treat the output as a well-informed estimate — always cross-check with local regulations, product datasheets, or a qualified electrical professional before committing to a purchase or a job.

What inputs does the Voltage Drop Calculator need?

Enter values for: One-way cable length (m), Current (A), Conductor area (mm²), Conductor, System voltage (V). Sensible defaults are pre-filled where possible so you can start with a single change.

Can I embed the Voltage Drop Calculator on my own website?

Yes — copy the iframe snippet at the bottom of this page, or use the Embed Generator to customise the size. The embedded version stays in sync with the live calculator on Calcora.