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Electrical Calculators

Watt-Hours (kWh) Calculator

Verified formula Updated Jun 2026 Private — runs on your device

Enter details
W
hours
Verified formula Private

Energy used

0.3000

In watt-hours
300.0

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Watt-Hours (kWh) Calculator

The Watt-Hours (kWh) Calculator works out your energy used, along with 1 related figure in an instant. Enter power and time used and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

  1. Enter the power.
  2. Enter the time used.
  3. Read off your energy used, together with in watt-hours — the calculator updates automatically, with no button to press.

Formula

The Watt-Hours (kWh) Calculator uses the formula:

Energy used = Power × Time used ÷ 1000

Worked example

For example, with power of 60 W and time used of 5 hours, the energy used is 0.3000.

Inputs used
Power 60 W
Time used 5 hours
Results
Energy used 0.3000
In watt-hours 300.0

Results are estimates for educational use, not professional advice.

Frequently asked questions

Multiply power in watts by the hours used. A 60 W device for 5 hours uses 300 watt-hours, or 0.3 kWh.

One kilowatt-hour equals 1000 watt-hours, the unit your electricity bill usually charges by.

Electricity is billed per kWh, so converting lets you estimate the cost of running a device.

Yes. Battery capacity is often given in watt-hours, so this helps estimate run time and energy storage.

Enter the power. Enter the time used. Read off your energy used, together with in watt-hours — the calculator updates automatically, with no button to press.

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