What Is a Kilowatt-Hour (kWh)? A Plain English Explanation

Two words sit inside the unit. A watt measures power, the rate at which a device uses energy at one moment. A kilowatt is 1,000 watts. An hour is how long the device runs. Multiply the two and you get energy: kilowatts times hours gives kilowatt-hours.

A useful comparison is a car. Power is the speed on the dashboard, and energy is the distance driven. A device that draws 2,000 watts for half an hour uses the same energy as one that draws 1,000 watts for one hour: 1 kWh.

Wattages are round numbers for illustration. Your own devices list their watts on a label.

The price per kWh depends on where you live and which plan you are on. The 2025 US residential average was 17.23 cents. State averages ranged from 11.82 cents in North Dakota to 40.40 cents in Hawaii. At the national average, 100 kWh costs about $17.23 and 1,000 kWh costs about $172.35.

Look up your own state on the electricity rates page, or divide a recent bill total by its kWh for your exact all-in price.

Source: U.S. Energy Information Administration, Form EIA-861 (final 2025 data), residential sector.

1. Take the watts on the device label.
2. Divide by 1,000 to get kilowatts.
3. Multiply by the hours it runs.

A 1,500 watt heater that runs 3 hours uses 1.5 times 3, which is 4.5 kWh. At the US average price that costs about $0.78. The kWh calculator does the steps for you, and it also takes amps and volts. Natural gas bills use a different unit, the therm, which the therm guide converts to kWh.

A utility meter adds up the energy that passes through it all day and night. A digital meter shows a running total on a small screen, and it cycles through several displays. The total is the one labeled kWh. A smart meter also sends its readings to the utility on a regular schedule, often every hour or less, so the utility can bill you without a visit.

Older meters use dials. Read them from left to right, and when a pointer sits between two numbers, write down the lower one. The dials turn in alternating directions, so check each arrow. To find how much you used between two dates, subtract the earlier reading from the later one. That difference is your kWh for the period, and it matches the usage line on your bill.

The average US home used about 28.8 kWh a day in 2025. Here is how some familiar loads compare with that:

Source: Price: 17.23 cents per kWh, the 2025 US average. Wattages are illustrative round numbers.

The point of the table is scale. A single dryer load uses about a tenth of what the whole average home uses in a day, while lighting and a laptop barely register. That is why the biggest savings come from a few large loads, not from many small ones.

A kW is a rate and a kWh is an amount. A solar panel system rated at 6 kW can produce up to 6 kWh in an hour of strong sun. A battery rated at 13 kWh can supply 1 kW for 13 hours. When a page or a salesperson quotes only one of the two, ask which one it is, because they answer different questions.

• U.S. Energy Information Administration, Form EIA-861 (final 2025 data)