Quick answer
A kilowatt-hour (kWh) is a unit of energy equal to 1,000 watts of power used for one hour, and it is the unit utilities use to bill you for electricity.
A 100-watt load running for 10 hours uses 1 kWh, and so does a 2,000-watt heater in 30 minutes. Your meter counts kWh. Your bill multiplies them by your rate, then adds fixed fees.
Quick facts
The key facts about Kilowatt-Hour (kWh), with sources:
Key takeaways
- A kWh is energy, not power: watts multiplied by hours, divided by 1,000.
- The kWh is what your meter counts and what your utility charges for.
- The average US home bought about 899 kWh a month in 2022, the EIA reports.
- Prices per kWh vary by state, from 12.72¢ in Louisiana to 48.00¢ in Hawaii in July 2026.
- Heating, cooling, water heating and EV charging drive most kWh in a home.
A kilowatt-hour in plain terms
The EIA puts it in one line: one kWh is one kilowatt generated for one hour 1. Since a kilowatt is 1,000 watts, a kWh is 1,000 watt-hours.
The EIA gives an example. A 40-watt bulb used for five hours uses 200 watt-hours, or 0.2 kWh 1. Five of those bulbs for the same five hours use one full kWh.
People often mix up kW and kWh. A kilowatt is a rate, like miles per hour. A kilowatt-hour is an amount, like miles driven. Your bill charges for the amount.
How kWh are counted
The meter at your home adds up energy as it flows in. Older meters did this with a spinning disk. Smart meters do it electronically and send readings to the utility. Each month the utility subtracts last month’s reading from this month’s to get your kWh.
You can estimate the kWh of any appliance yourself. Virginia Tech Extension gives the method: multiply wattage by hours used per day and divide by 1,000 for daily kWh. Then multiply by the days used per year 4.
- Read wattsFrom the appliance label
- Multiply by hoursHow long it runs each day
- Divide by 1,000Gives kWh per day
- Multiply by daysGives kWh per month or year
- Multiply by your rateGives the energy part of the bill
Source: [4]
Energy units from small to large
| Unit | Equals | Where it shows up |
|---|---|---|
| Watt-hour (Wh) | One watt for one hour | Phone and laptop batteries |
| Kilowatt-hour (kWh) | 1,000 Wh 1 | Home bills, EV battery size |
| Megawatt-hour (MWh) | 1,000 kWh | Power plant output, large buildings |
| Gigawatt-hour (GWh) | 1,000,000 kWh | Utility and state energy totals |
| Kilowatt (kW) | A rate, not an amount | Demand charges, charger and solar sizes |
Example: a computer setup over a year
Virginia Tech Extension works this example: a 120 W computer and a 150 W monitor used 4 hours a day for 365 days 4. We price it at the EIA US average for July 2026 3.
| Step | Math | Result |
|---|---|---|
| Combined watts | 120 + 150 | 270 W |
| Daily energy | 270 × 4 ÷ 1,000 | 1.08 kWh |
| Yearly energy | 1.08 × 365 | About 394 kWh |
| Yearly cost at 18.31¢ | 394 × $0.1831 | About $72 |
| Same in Hawaii at 48.00¢ | 394 × $0.48 | About $189 |
The extension priced the same 394 kWh at an older 8.5-cent rate, which shows how rates have moved. This is labelled arithmetic, not a quote. Use the rate on your own bill.
Where kWh appear on your bill
Look for “usage,” “kWh used” or “energy charge.” The bill shows the meter readings, the kWh between them and a price per kWh. Many bills add a 12-month bar chart of your use.
Some rates charge different prices at different times of day. Some add tiers, where kWh above a set amount cost more. A few charge for demand in kW as well. Your utility’s rate sheet explains each line.
EV and battery specs use kWh too. A car battery listed at 60 kWh holds about as much energy as a typical home uses in two days.
Why kWh is a useful number
What it lets you do
- Compare appliances on real yearly energy, not just labels.
- Check a bill against your own estimate.
- Size a battery or solar system against real use.
- Track the effect of changes, such as a new heat pump.
What it misses
- It hides when energy is used, which matters on time-of-use rates.
- It does not show peak demand, which sets wire and panel needs.
- Bills add fixed fees, so cost does not scale exactly with kWh.
What kWh do not tell an electrician
Two homes can use the same kWh per month and need very different panels. One spreads its use evenly. The other runs a dryer, oven and EV charger at once.
Wiring is sized for the peak in amps, not the monthly total. That is why electricians use a load calculation, not your bill, to size a service.
The EIA also notes its household figures are purchases from utilities. In states with many rooftop solar systems, they can understate real use 2.
What drives your cost per kWh and total bill
We do not set or quote rates. These factors move what you pay. Our cost guides cover the price of electrical work.
- Your state and utility. July 2026 averages ranged from 12.72¢ to 48.00¢ 3.
- Rate design. Flat, tiered and time-of-use rates price the same kWh differently.
- Climate. Heating and cooling loads raise kWh in hot and cold regions.
- Electric heat and water heating. Big users in all-electric homes.
- EV charging. Adds kWh every month. Our EV charging cost calculator estimates it.
How to find your own kWh use
- Pull 12 months of bills, or download usage from your utility account.
- Add the kWh to get a yearly total, and note the highest month.
- Divide the yearly total by 12 to compare with the EIA average of about 899 kWh a month 2.
- Estimate big loads with watts × hours ÷ 1,000 4.
- Use the totals when you plan solar, a battery or an EV, and share them with your installer.
Habits that cut kWh safely
- Unplug devices with high standby draw when not in use.
- Run dishwashers and dryers with full loads.
- Switch to LED bulbs, which give the same light at fewer watts.
- Keep fridge coils clean so the compressor runs less.
- Watch for a sudden jump in kWh. It can point to a failing appliance or a wiring fault.
When a kWh jump is a warning sign
A sharp rise in kWh with no change in habits can mean a stuck heating element, a failing well pump or a water heater that runs nonstop.
If an appliance runs hot, smells of burning or trips its breaker, unplug it.
The CPSC says to unplug anything that repeatedly trips a breaker or gives a shock and have it repaired or replaced 6.
Do not hunt for the cause inside panels or appliances. Call an electrician or an appliance tech.
High use plus heat is a fire risk
A circuit that carries heavy load for hours can overheat at weak connections. Warm outlets, scorch marks or a burning smell call for an electrician right away; smoke or flame calls for 911.
Who regulates kWh pricing and metering
State utility commissions approve the rates investor-owned utilities charge per kWh. Co-ops and city utilities set rates through their boards. Meters must meet accuracy standards set by the utility and the state.
Building wiring follows the National Electrical Code, which deals in amps and volts rather than kWh. The 2026 edition is free to read online 7. Federal data on prices and use comes from the EIA 3.
kWh compared with related terms
| Term | Kind of quantity | Example |
|---|---|---|
| Kilowatt-hour | Energy (amount) | 899 kWh in a month |
| Watt / kilowatt | Power (rate) | A 1.5 kW heater |
| Amp | Current | 12.5 A for that heater at 120 V |
| Volt | Electrical push | 120 V outlet |
| Therm | Gas energy (not electric) | Gas bill unit |
Myths about kilowatt-hours
- Myth kW and kWh mean the same thing.
- Reality kW is a rate; kWh is an amount used over time.
- Myth A bigger panel raises your kWh.
- Reality Panel size sets how much you can draw at once. Use sets the kWh.
- Myth Turning things off and on uses more energy than leaving them on.
- Reality For lights and most electronics, off uses less.
- Myth Price per kWh is the same everywhere.
- Reality In July 2026 Hawaii paid nearly four times Louisiana’s average 3.
What changes by state
When kWh matter to you
Kilowatt-hours matter when you compare bills, plan solar or a battery, add an EV or switch to electric heat. For bills and running costs, think in kWh. For wiring and panels, think in amps and kW; start with the electrification readiness check.
Quick conversion
Divide an appliance’s watts by 1,000 to get kW. That is how many kWh it uses in one hour of full-power running.
Questions about Kilowatt-Hour (kWh)
What is a kilowatt-hour?
A kilowatt-hour is a unit of energy equal to one kilowatt, or 1,000 watts, used for one hour. The EIA says utilities generally measure and bill electricity in kWh. A 100-watt bulb running for 10 hours uses one kWh.
How do I calculate kWh?
Multiply the appliance’s watts by the hours it runs, then divide by 1,000. Virginia Tech Extension uses this method. A 1,500-watt heater running 4 hours uses 6 kWh. Multiply by days used to get monthly or yearly kWh.
How many kWh does an average house use per month?
About 899 kWh a month, based on the EIA figure of 10,791 kWh a year in 2022. State averages differ a lot. Louisiana homes averaged 14,774 kWh a year and Hawaii homes 6,178 kWh.
How much does a kWh cost?
The EIA reports a US average residential price of 18.31 cents per kWh for July 2026, a preliminary figure. State averages ranged from 12.72 cents in Louisiana to 48.00 cents in Hawaii. Your exact rate is on your bill or your utility’s rate sheet.
What is the difference between kW and kWh?
A kilowatt measures power, the rate of use at a moment. A kilowatt-hour measures energy, the total used over time. A 2 kW heater running for 3 hours uses 6 kWh. Bills charge for kWh; panels and chargers are sized in kW and amps.
How many kWh does it take to charge an electric car?
It depends on battery size and how empty it is. The DOE says Level 1 charging at about 1.9 kW adds roughly 5 miles of range per hour, so one hour of Level 1 uses about 1.9 kWh. Use the EV charging cost calculator with your car and rate.
Why is my kWh usage so high?
Common causes are heating or cooling in extreme weather, an electric water heater, a pool pump, an EV, or an old fridge or freezer. A sudden jump with no change in habits can mean a failing appliance. Compare month to month on your bill, then check big loads.
Is a kWh the same as a unit of electricity?
Yes. In many countries a “unit” on the bill means one kilowatt-hour. US bills usually say kWh. Either way, it is 1,000 watts used for one hour.
How many kWh does a refrigerator use a day?
Virginia Tech Extension lists a 16 cubic foot frost-free fridge at 725 watts and says to divide plugged-in hours by three for cycling. That gives 725 W × 8 h ÷ 1,000, or about 5.8 kWh a day, as a rough upper estimate. Newer models often use less.
Sources
- U.S. Energy Information Administration, Electricity explained: Measuring electricity, retrieved .
- U.S. Energy Information Administration, FAQ: How much electricity does an American home use?, retrieved .
- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A (July 2026 preliminary), retrieved .
- Virginia Cooperative Extension, How to Estimate Appliance Energy Use (pub. 2901-9014), retrieved .
- U.S. DOE Alternative Fuels Data Center, Developing Infrastructure to Charge Electric Vehicles, retrieved .
- U.S. CPSC, CPSC and NESF Urge Consumers to Plug Into Electrical Safety (2000), retrieved .
- NFPA 70, National Electrical Code, 2026 edition (free access), retrieved .
Expert review
Written by the HyreElectrical Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Definitions and use figures from EIA; method and appliance example from Virginia Cooperative Extension; prices from EIA Table 5.6.A. Cost rows are labelled example arithmetic.
Suggest a correction. We fix errors and say what changed.