Find how much voltage is lost along a cable run, the voltage at the far end and the power wasted as heat.
loading toolHow to use the voltage drop calculator
- Type your numbers in the boxes (pick your currency or units if asked).
- The answer updates as you type: no button to press.
- Copy the result, or share it on WhatsApp with one tap.
Questions
How much drop is allowed?
A common guide is 3% for lighting and 5% for other circuits; check your country’s wiring rules.
Is my data private?
Yes. Everything happens inside your own browser: nothing you type or choose is uploaded to us or anyone else.
Is it free?
Completely free, with no sign-up, no watermark and no limit on how many times you use it. Light ads keep the site running.
