Find the minimum cable cross-section for your current, voltage and run length at an acceptable voltage drop.
Tell us what you need to power and we will confirm the exact model, voltage and configuration — usually within 24 hours.
A cable has to pass two independent tests. First, ampacity — can it carry the current without overheating? Second, voltage drop — does the load still receive enough voltage at the far end? On short runs ampacity usually governs. On long runs, voltage drop takes over, and you end up with a cable far thicker than the current alone would suggest.
This calculator works from the voltage drop side: you set the maximum acceptable drop and it returns the smallest standard cross-section that stays within it.
Sizes are taken from the standard series: 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120 mm² and above. The result is always rounded up to the next size, never down.
Because of distance. A 32 A load over 50 m at 400 V needs a much larger conductor than the same load over 10 m. Increasing the cross-section is usually cheaper than accepting the losses over the life of the installation.
Aluminium needs roughly 1.6 times the cross-section of copper for the same voltage drop, but it costs less and weighs much less. For large fixed runs aluminium is common; for everything else copper is the simpler choice.
No. It is an indicative value for PVC-insulated copper in free air at 30 °C. Derate it for higher ambient temperatures, grouping with other cables, and installation in conduit or insulation.
