Part of the topic: 🏠 Home, energy & car
Voltage drop & cable size calculator
Enter system, one-way cable length, current and cross-section. The calculator shows the voltage drop and the smallest standard cross-section that keeps it below your limit.
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🔒 Runs entirely in your browser – nothing you enter is uploaded or stored.
How to use it
- Choose single-phase or three-phase.
- Enter the one-way length, current, cos φ and the planned cross-section.
- Check the voltage drop and the minimum cross-section for your limit.
Last checked: October 2026 · Based on: Voltage drop formulas; DIN 18015-1 (3 % guide value), DIN VDE 0100-520. Found a mistake? Use the form below – we fix confirmed errors and update the date.
Frequently asked questions
What voltage drop is allowed?
In German residential installations 3 % between meter and consumer is a common guide value (DIN 18015-1); for long PV or charging cables lower values are often planned.
Why the factor 2 for single-phase?
Current flows to the consumer and back – the conductor length is twice the cable length.
Does this replace sizing by an electrician?
No. It only checks the voltage drop; current-carrying capacity and protection must be planned per DIN VDE 0100.