A watt-hour (Wh) is a unit of energy. It measures the total amount of energy used or produced over time.

How it works:

  • Power (watts) × time (hours) = energy (watt-hours).

Example:
A 10‑watt light bulb running for 1 hour consumes 10 Wh of energy.

Relationship to other units:

  • 1 kilowatt‑hour (kWh) = 1,000 Wh (used for home electricity bills).

  • 1 watt‑hour = 3,600 joules (since 1 W = 1 J/s, and 1 hour = 3,600 s).

In short: watt‑hours tell you how much electricity is used or stored, not just the rate of use (watts).