Enter the current, cable run and voltage to get the minimum cross-section (mm² & AWG) and the real voltage drop — copper or aluminium.
Undersized cable runs hot and loses voltage; oversized cable wastes money. This wire size calculator finds the minimum cross-section from your current, cable length and a target voltage drop. For a single-phase run the minimum area is 2 × resistivity × length × current ÷ allowed drop (V); three-phase uses a √3 factor. It rounds up to the nearest standard mm², shows the AWG equivalent, and reports the actual voltage drop you'll get.
Keep total voltage drop under about 3% for lighting and 5% for power. Copper carries more current than the same size aluminium. This is a planning estimate — the final cable must also satisfy your local current-carrying capacity, grouping, temperature and protection rules. Always follow the wiring regulations for your country.
Related: Unit Converter · Metal Weight Calculator