Convert kilowatt-hours to joules
Kilowatt-hour (kWh) to joule (J). One kilowatt-hour equals 3600000 joules.
Formula
Kilowatt-hour to joule conversion table
| Kilowatt-hours | Joules | Joules | Kilowatt-hours |
|---|---|---|---|
| 1 kWh | 3600000 J | 1 J | 2.777778e-7 kWh |
| 2 kWh | 7200000 J | 2 J | 5.555556e-7 kWh |
| 3 kWh | 10800000 J | 3 J | 8.333333e-7 kWh |
| 5 kWh | 18000000 J | 5 J | 0.000001 kWh |
| 10 kWh | 36000000 J | 10 J | 0.000003 kWh |
| 20 kWh | 72000000 J | 20 J | 0.000006 kWh |
| 50 kWh | 180000000 J | 50 J | 0.000014 kWh |
| 100 kWh | 360000000 J | 100 J | 0.000028 kWh |
| 500 kWh | 1800000000 J | 500 J | 0.000139 kWh |
| 1000 kWh | 3600000000 J | 1000 J | 0.000278 kWh |
To convert kilowatt-hours to joules, multiply the number of kilowatt-hours by 3600000. One kilowatt-hour equals 3600000 joules, and one joule equals 2.777778e-7 kilowatt-hours, so the relationship is fixed and exact. As a worked example, 10 kWh comes to 36000000 J. Enter your own figure in the converter above to get an instant answer, or use the swap button to flip the direction. This is a energy conversion, and like every tool on UnitGlide it runs locally in your browser with no account or upload required. The table further down shows a range of common kilowatt-hour values already worked out in joules, plus the reverse joule to kilowatt-hour direction, which is handy for quick reference or double-checking a result by hand.
Kilowatt-hour to joule in practice
Kilowatt-hours to joules connects the unit on an electricity bill to the unit in a physics textbook, spanning a factor of several million.
From the meter to the equation
Electricity is billed in kilowatt-hours, but energy calculations want joules, so a 2 kWh dishwasher cycle is 7.2 million joules and a 0.5 kWh laptop charge is 1.8 million. Battery capacities quoted in kWh convert the same way when you need the stored energy in SI units, which is how an electric-car pack of 60 kWh becomes 216 million joules on paper.
Energy, not power
The trap is treating kWh as if it were kilowatts. A kilowatt is a rate of using energy; a kilowatt-hour is the energy used at that rate over an hour. A 2 kW heater run for three hours uses 6 kWh, and it is the kWh, not the kW, that becomes joules. Confusing the two mixes an amount with a speed and gives a meaningless figure.
An exact factor
One kilowatt-hour is exactly 3,600,000 joules, because an hour is 3,600 seconds and a watt is one joule per second. There is no rounding hidden in the factor itself, only in how many digits you choose to display, so even a fractional kWh converts to joules without introducing error.
Scaling to megajoules
Because the joule figures run into the millions, it is often tidier to read the answer in megajoules: 1 kWh is 3.6 MJ, so a 5 kWh tumble-dryer load is 18 MJ. Gas energy is frequently quoted in MJ, so shifting a kWh reading into megajoules makes an electricity figure directly comparable with a gas one.
Sizing a physics problem
Homework and engineering estimates often start from an appliance's kWh and ask for the work done in joules or the heat released, and the millionfold jump is where answers go astray. A kettle rated at 0.1 kWh per boil is 360,000 joules, plenty to raise a litre of water by the expected amount, and checking that the joule figure is in the hundreds of thousands, not the hundreds, catches a slipped factor early.
Frequently asked questions
How many joules are in a kilowatt-hour?
One kilowatt-hour equals 3600000 joules. The ratio is constant, so you can multiply any number of kilowatt-hours by 3600000 to get joules.
What is the formula to convert kilowatt-hours to joules?
Use joules = kilowatt-hours × 3600000. UnitGlide applies this exact formula for every value, so results stay accurate across the whole range.
How do I convert joules back to kilowatt-hours?
Go the other way by using one joule equals 2.777778e-7 kilowatt-hours. You can also press the swap button in the converter above to flip the direction in one click.
Is this kilowatt-hour to joule converter accurate?
Yes. It uses internationally defined SI conversion factors, as maintained by the BIPM, and all math runs in your browser so nothing is rounded away on a server. For everyday use the displayed precision is more than enough.