kWh to Wh Converter

One kilowatt-hour equals 1000 watt-hours (Wh). To convert kilowatt-hours to watt-hours, multiply by 1000; to go back the other way, multiply by 0.001 instead.

The converter above does it as you type and shows the working underneath, so you can check the arithmetic rather than take the number on trust.

What kilowatt-hours and watt-hours actually measure

Kilowatt-hour (kWh) — A kilowatt-hour is a thousand watt-hours, or 3.6 megajoules. Electricity billing everywhere, and EV battery capacity.

Watt-hour (Wh) — A watt-hour is one watt sustained for one hour — 3,600 joules. Battery capacity for laptops, phones and power banks.

kWh to Wh conversion table

The most common values, worked out in advance. Anything not listed can be typed straight into the converter.

How to convert kilowatt-hours to watt-hours by hand

Multiply the number of kilowatt-hours by 1000.

For example, 25 kWh × 1000 = 25000 Wh.

Going the other way, divide by 1000 — or multiply by 0.001, which is the same thing and easier to do in your head.

Everything runs in your browser

There is no server involved in the calculation. The numbers you type never leave your device, nothing is logged, and the page keeps working with no connection once it has loaded. That is not a marketing line — it is simply how the tool is built, because a calculation like this has no reason to touch a network.