What Is a kWh? Kilowatt-Hours Explained Simply

Every electricity bill in America is measured in one unit: the kilowatt-hour, or kWh. It's the single most useful number to understand about your energy use, because it's literally what you pay for. Yet most people never learn what it actually means. The short version: a kWh is 1,000 watts of power used for one hour — a measure of energy, the total amount of electricity consumed. This guide explains what a kWh is, how it differs from a kilowatt, how to calculate it, and what one kWh costs and powers.

The simple definition

A kilowatt-hour (kWh) is a unit of energy. One kWh equals 1,000 watts running for one hour.

That's it. The name spells out the math: kilowatt (1,000 watts of power) × hour (one hour of time) = kilowatt-hour. So:

• A 1,000-watt microwave running for 1 hour = 1 kWh
• A 100-watt bulb running for 10 hours = 1 kWh
• A 2,000-watt heater running for 30 minutes = 1 kWh

All three consume the same total energy — one kWh — because kWh measures the combination of how much power and how long, not just one or the other. This is why your utility bills in kWh: it captures your total consumption in a single number.

kW vs. kWh: the distinction that trips everyone up

The most common confusion is between a kW and a kWh. They sound alike but measure different things:

• Kilowatt (kW) = power. The rate at which energy is used, right now. It's an instantaneous measure.
• Kilowatt-hour (kWh) = energy. The total amount used over a stretch of time.

The classic analogy is a car:

• kW is like speed (miles per hour) — how fast you're going at this instant.
• kWh is like distance (miles traveled) — the total covered over the trip.

A 5 kW oven draws power at 5 kW the whole time it's on. Run it for two hours and it consumes energy of 5 kW × 2 h = 10 kWh. Your utility doesn't charge for the 5 kW rate — it charges for the 10 kWh total. Power tells you how hard a device pulls; energy (kWh) tells you the bill.

How to calculate kWh

You can figure the energy any appliance uses from two numbers — its wattage (on the label or spec sheet) and the hours you run it:

kWh = watts × hours ÷ 1,000

Dividing by 1,000 converts watts to kilowatts. A few examples:

To turn kWh into dollars, multiply by your rate:

Cost = kWh × your rate per kWh

So that space heater at 6 kWh, at a 17¢ rate, costs 6 × $0.17 = about $1.02. The electricity cost calculator does this for any device, and the electricity bill estimator adds up a whole home.

What does 1 kWh cost?

In the US, one kWh costs roughly 13 to 25 cents, with a national average around 17 cents. It varies widely by state and utility:

• Low-cost states sit near 11–13¢/kWh.
• High-cost states can exceed 30¢/kWh.

Your exact price is printed on your bill as a rate per kWh (sometimes split into supply and delivery charges that add up). See how states compare on our electricity rates page. That per-kWh number, times the kWh you use, is the usage part of your bill — on top of it sit fixed monthly charges and taxes that you pay regardless of usage.

What can 1 kWh actually power?

To make a kWh tangible, one kWh is enough to:

• Run a refrigerator for about 6–8 hours
• Power a 65-inch LED TV for around 10 hours
• Do about one load in an efficient dishwasher
• Drive an EV roughly 3–4 miles
• Run a 1,500-watt space heater for 40 minutes
• Light a 10-watt LED bulb for 100 hours

That range — from 100 hours of a light bulb to 40 minutes of a space heater — shows why high-wattage devices dominate a bill. The cost to run reference lists real kWh and dollar figures for dozens of common appliances.

How many kWh does a home use?

A typical US home uses roughly 25–35 kWh per day, or about 850–950 kWh per month — but the spread is enormous:

• A small apartment with gas heat might use ~10 kWh/day.
• A large all-electric home with heavy AC or an EV can use 50+ kWh/day.

The difference is almost entirely heating, cooling, and water heating — the highest-wattage, longest-running loads. That's why, if you want to lower a bill, those are the first place to look — covered in how to estimate and lower your electricity bill and why is my electric bill so high.

The bottom line

A kWh (kilowatt-hour) is the unit of energy your electricity is measured and billed in — 1,000 watts used for one hour. Keep the key distinction straight: kW is power (the rate, like speed), kWh is energy (the total, like distance), and your bill charges for the total. Calculate any device's usage with watts × hours ÷ 1,000, multiply by your rate (around 17¢ on average) for the cost, and you can decode your entire electric bill. Put your own numbers in with the calculators below.