Watt (W)
The watt explained: one joule per second, how it relates to volts and amps, the kilowatt-hour on your bill, and horsepower conversion.
Questions people ask
What is the difference between a watt and a watt-hour?
A watt is a rate; a watt-hour is an amount. A 100 W bulb burning for ten hours uses 1000 Wh, or 1 kWh — and that is what you are billed for.
Why are speakers rated in watts?
It is the electrical power they can handle without damage, not how loud they are. Doubling the watts adds only about 3 dB, which is a barely noticeable change in level.
Does this page work offline?
Yes, after the first visit. The service worker caches it, so the reference stays available with no connection.
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Last updated 22 August 2026