Kilowatt-hours to Joules Converter
Convert kilowatt-hours from your energy bill into joules, megajoules, and watt-hours.
How the conversion works
A kilowatt-hour is the unit your electricity meter records: 1,000 watts sustained for one hour. Because one watt is one joule per second, a kilowatt-hour equals 1,000 × 3,600 = 3,600,000 joules.
To convert any kWh figure to joules, multiply by 3,600,000. This is useful when you want to compare a household energy figure against scientific values quoted in joules or megajoules.
J = kWh × 3,600,0001 kWh = 3,600 kJ = 3.6 MJ = 3,600,000 J
Conversion table
| Kilowatt-hours | Joules | Megajoules |
|---|---|---|
| 0.1 kWh | 360,000 J | 0.36 MJ |
| 0.5 kWh | 1,800,000 J | 1.8 MJ |
| 1 kWh | 3,600,000 J | 3.6 MJ |
| 2 kWh | 7,200,000 J | 7.2 MJ |
| 5 kWh | 18,000,000 J | 18 MJ |
| 10 kWh | 36,000,000 J | 36 MJ |
| 50 kWh | 180,000,000 J | 180 MJ |
Frequently asked questions
How many joules are in 1 kWh?
One kilowatt-hour equals exactly 3,600,000 joules (3.6 megajoules). It is 1,000 watts of power sustained for one hour of 3,600 seconds.
How do you convert kWh to joules?
Multiply the number of kilowatt-hours by 3,600,000. For example, 2.5 kWh × 3,600,000 = 9,000,000 joules.
Why is a kWh so many joules?
Because the joule is a very small unit. A single joule is roughly the energy to lift an apple one metre, so household-scale energy runs into the millions of joules — which is why meters use kWh instead.