Watts to kWh per year converter
Convert what a device draws in watts to the kWh it uses per day, month or year when it runs all the time, or a kWh figure back to watts.
That's about the same as a Wi-Fi router. At 0.30 per kWh, running it all year costs about 26.3.
What it means
How much power is that?
Assumes the device runs around the clock at that average power. The cost uses 0.30 per kWh in any currency.
Every unit
That power in every period
Learn
Three things worth knowing
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1 W ≈ 9 kWh a year
Every watt that stays on uses 8.77 kWh a year. At 0.30 per kWh, each always-on watt costs about 2.60 a year.
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Edison’s meter
Thomas Edison’s first customers in 1882 were billed by lamp; his chemical meter, weighing zinc plated by the current, made billing by energy possible.
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kW is not kWh
A 2 kW heater does not use 2 kWh unless it runs for an hour. Watts say how fast, kWh how much.
Shortcuts
Popular power draw conversions
Background
About watts and kWh
A watt is a rate; a kilowatt-hour is an amount. A device drawing 1,000 W for an hour uses 1 kWh. Something that is always on, a router, a fridge, standby lights, adds up: 1 W running all year is 8.77 kWh.
Energy labels give kWh per year; plugs and meters show watts. This converter links the two.