On long cable runs the wire itself steals some of your voltage, and too much drop means dim lights, sluggish motors or resets. This calculator estimates that loss. It takes the one way run length, the load current, the wire cross section and the conductor material, then computes the resistance of the round trip and multiplies by the current to give the voltage dropped in the cable. The result is shown as volts lost, the voltage that actually reaches the load, and the drop as a percentage of your supply, since a common rule of thumb keeps the drop under three percent for a healthy circuit. Choose copper or aluminium and enter your numbers to size a cable properly for a solar run, a battery lead, low voltage lighting, or an audio feed. Everything runs locally in your browser, so it is instant and private.
On long cable runs the wire itself steals some of your voltage, and too much drop means dim lights, sluggish motors or resets. This calculator estimates that loss.
Yes. Voltage Drop Calculator is completely free, with no sign-up and no usage limits.
Yes. Voltage Drop Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Voltage Drop Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.