Convert Kilowatt-Hours to Joules
Kilowatt-hours to joules is the conversion you need when the unit on your electricity bill has to meet the base energy unit used in physics. A kilowatt-hour is what you use when 1000 watts run for one hour, and one kilowatt-hour is exactly 3,600,000 joules — so the joule number comes out very large.
Kilowatt-hours to Joules conversion table
| Kilowatt-hours (kWh) | Joules (J) |
|---|---|
| 1 | 3,600,000 |
| 2 | 7,200,000 |
| 3 | 10,800,000 |
| 5 | 18,000,000 |
| 10 | 36,000,000 |
| 20 | 72,000,000 |
| 50 | 180,000,000 |
| 100 | 360,000,000 |
| 500 | 1,800,000,000 |
| 1,000 | 3,600,000,000 |
The formula
To convert kilowatt-hours to joules, multiply the number of kilowatt-hours by 3,600,000:
joules = kilowatt-hours × 3,600,000
A worked example
Say you used 2 kilowatt-hours and want it in joules:
2 × 3,600,000 = 7,200,000 J
So 2 kilowatt-hours is exactly 7,200,000 joules.
Why the number is exact
A kilowatt-hour is 1000 watts running for one hour, and a watt is defined as one joule per second. One hour is exactly 3600 seconds, so a kilowatt-hour is 1000 × 3600 joules — exactly 3,600,000. Every piece of that is a defined, whole number, so the conversion is exact, not rounded.
When you'll use it
Bridging your electricity bill to physics or engineering work, checking energy-storage and battery figures, or comparing a household's usage against joule-based numbers in a textbook or datasheet.
Frequently asked questions
How many joules are in a kilowatt-hour?
Exactly 3,600,000 joules. A kilowatt-hour is 1000 watts running for 3600 seconds, and a watt is a joule per second, so 1000 × 3600 gives exactly 3,600,000 joules — nothing rounded.
What is a kilowatt-hour, in plain terms?
It's the unit on your electricity bill: the energy used when a 1000-watt load runs for one full hour. A microwave, a hair dryer, or ten 100-watt bulbs for an hour each use about one kilowatt-hour.
Is the kilowatt-hours to joules conversion exact?
Yes. A kilowatt-hour is defined as 1000 watts for 3600 seconds, and both pieces are exact, so one kilowatt-hour is exactly 3,600,000 joules with nothing rounded away.