Kilowatt-Hours to Joules Converter
Convert kilowatt-hours to joules and back instantly.
Conversion Result
Quick Reference: kWh to Joules
| Kilowatt-hours (kWh) | Joules (J) | Megajoules (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 |
The Conversion Factor
A kilowatt-hour (kWh) is a unit of energy equal to one kilowatt of power sustained for one hour. Because one watt equals one joule per second, a kilowatt equals 1,000 joules per second, and one hour contains 3,600 seconds. Multiplying these together gives the exact relationship:
- 1 kWh = 1,000 W × 3,600 s = 3,600,000 J
- 1 kWh = 3.6 megajoules (MJ)
- To convert kWh to J: multiply by 3,600,000
- To convert J to kWh: divide by 3,600,000
Energy on Your Power Bill
Electricity providers bill energy consumption in kilowatt-hours because the joule is too small a unit for household use — a single kWh equals 3.6 million joules. When you see a charge for "350 kWh" on a monthly statement, that represents 1.26 billion joules of electrical energy. The kilowatt-hour is convenient because it ties directly to appliance power ratings: a 100-watt bulb left on for 10 hours uses exactly 1 kWh, while a 2,000-watt heater running for 30 minutes also uses 1 kWh. Converting to joules is useful when comparing electricity to other energy forms measured in SI units, such as the chemical energy in fuel or food.
Common Uses
Converting between kilowatt-hours and joules comes up across many fields:
- Physics and engineering: Expressing electrical energy in the SI base unit (the joule) for calculations and reports.
- Energy comparisons: Comparing battery capacity, fuel energy, and electricity on a common scale.
- Education: Demonstrating how power, time, and energy relate through P × t = E.
- Renewables and storage: Sizing solar systems and battery banks where datasheets mix kWh and joule-based figures.