kW vs. kWh: The Difference, in Plain English
A kilowatt (kW) is a rate: how fast something uses electricity at this moment. A kilowatt-hour (kWh) is an amount: how much electricity was used over time. Your bill charges for kilowatt-hours.
Key points
- kW is how fast electricity is being used; kWh is how much was used.
- kW × hours = kWh.
- Your bill charges for kWh. The U.S. average price is 18.31 cents each.
The speed and distance comparison
Think of a car. Miles per hour tells you how fast you are going; miles tells you how far you went. Watts and kilowatts are the speed. Kilowatt-hours are the distance.
A 1,000-watt (1 kW) heater running for one hour uses 1 kWh. Run it for three hours and it uses 3 kWh. A 100-watt television would need ten hours to use the same single kWh.
kW × hours = kWh. That is the only relationship you need.
Watts, kilowatts and the label on your appliance
The label on an appliance gives watts (W), because that is a property of the appliance: it describes how much power it draws when it is on. One kilowatt is simply 1,000 watts, in the same way a kilometer is 1,000 meters.
| Appliance | Watts | Kilowatts |
|---|---|---|
| LED bulb | 10 W | 0.01 kW |
| Television | 100 W | 0.1 kW |
| Refrigerator (compressor on) | 150 W | 0.15 kW |
| Microwave | 1,500 W | 1.5 kW |
| Space heater | 1,500 W | 1.5 kW |
| Clothes dryer | 3,000 W | 3 kW |
| Central air conditioner | 3,500 W | 3.5 kW |
The label cannot tell you kilowatt-hours, because that depends on how long you use the appliance. Only you know that.
Kilowatt-hours and your bill
Your meter counts kilowatt-hours, and your utility charges a price for each one. The U.S. average residential price is 18.31 cents per kWh (July 2026), so:
| Energy | What it is | Cost at the U.S. average |
|---|---|---|
| 1 kWh | A 1,500 W heater for 40 minutes, or a 100 W TV for 10 hours | $0.18 |
| 10 kWh | A 1,500 W space heater for 6 hours 40 minutes | $1.83 |
| 30 kWh | A typical full day for an average U.S. home | $5.49 |
| 863 kWh | The average U.S. home's month (2024) | $158.02 |
Prices vary a great deal by state. The rates by state table shows the price of one kWh where you live.
Amps and volts
Some labels give amps (A) instead of watts. Amps measure current and volts measure electrical pressure; multiplied together they give watts.
Volts × amps = watts. U.S. wall outlets supply about 120 volts, and large appliances such as dryers, ranges and water heaters use 240-volt circuits. A window air conditioner marked 7.5 A on a 120-volt outlet draws 7.5 × 120 = 900 watts.
A standard 15-amp household circuit can supply 15 × 120 = 1,800 watts in total. That is why 1,500 watts is the usual ceiling for plug-in heaters, hair dryers, kettles and air fryers, and why running two of them on the same circuit trips the breaker.
Bigger units: megawatts and megawatt-hours
Power plants and whole states are measured in the same units with larger prefixes. A megawatt (MW) is 1,000 kilowatts, and a megawatt-hour (MWh) is 1,000 kWh, roughly what an average U.S. home uses in five weeks.
To give a sense of scale, power plants in Texas generated about 566 million MWh in 2024, more than any other state, according to the Energy Information Administration. The principle is identical to the one on your bill: power multiplied by time.
Common confusions
- "kW per hour". This phrase is almost always a mistake for kWh. A kilowatt already is a rate.
- A higher wattage does not mean a higher bill. A 1,500 W kettle used for four minutes costs far less than a 150 W refrigerator running all day. See what uses the most electricity.
- kWh on an EnergyGuide label is per year. The yellow label on a new appliance shows estimated kWh per year; multiply by your price per kWh for the yearly cost.
- Batteries and solar panels use both. A battery's kWh is how much energy it holds; its kW is how fast it can deliver it. A solar array's kW is its peak output; the kWh it produces depends on the hours of sun.
Putting it to use
To find what any appliance costs to run: convert its watts to kilowatts, multiply by the hours you use it to get kWh, and multiply by your price per kWh. Our step-by-step guide works through examples, and the calculator does it for you.
Frequently asked questions
What is the difference between kW and kWh?
kW (kilowatt) is power: the rate at which electricity is used at a given moment. kWh (kilowatt-hour) is energy: the total used over time. A 2 kW appliance running for 3 hours uses 6 kWh.
How many watts are in a kilowatt?
1,000. To convert watts to kilowatts, divide by 1,000: a 1,500-watt heater is 1.5 kW.
How many kWh does a house use per day?
The average U.S. home used 863 kWh a month in 2024, according to the EIA, which is about 28 kWh a day.
Sources
- U.S. Energy Information Administration, Electric Power Monthly (state electricity prices)
- U.S. Energy Information Administration: Average monthly residential bill by state, 2024
- U.S. Department of Energy, Energy Saver: Appliances and Electronics
Electricity prices are the EIA figures for July 2026. Wattages are typical values; check the label on your own appliance.
Keep reading
- How to Calculate the Electricity Cost of Any Appliance
- How to Read Your Electric Bill and Find Your Real Price per kWh
- 12 Ways to Lower Your Electric Bill, Ranked by How Much They Save
- What Uses the Most Electricity in a Home? Biggest Loads Ranked
- Time-of-Use Electricity Rates Explained: Peak vs. Off-Peak
- Standby Power: What "Phantom Load" Really Costs
- Why Electricity Costs More in Some States Than Others
- How to Find the Wattage of Any Appliance
- Electricity rates by state