Wh to kWh Converter

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

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

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

Wh to kWh conversion table

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

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

Multiply the number of watt-hours by 0.001.

For example, 25 Wh × 0.001 = 0.025 kWh.

Going the other way, divide by 0.001 — or multiply by 1000, 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.