How Many Joules in a Kilowatt-Hour?
Quick Answer
There are 3,600,000 joules in one kilowatt-hour.
1 kWh = 1,000 W × 3,600 s = 3,600,000 J
Understanding the Conversion
One kilowatt-hour = 1,000 watts × 3,600 seconds = 3,600,000 joules (3.6 MJ). This is the exact conversion because watts (joules/second) × seconds = joules, and kWh = 1,000 W × 3,600 s. The joule is the SI unit of energy.
Formula
1 kWh = 1,000 W × 3,600 s = 3,600,000 J
Common Examples
| Description | Value |
|---|---|
| A 100W light bulb for 1 hour | 360,000 joules (0.1 kWh) |
| 1 kWh of electricity | 3.6 megajoules |
| Lifting 1 kg by 1 m | ≈9.8 joules (tiny!) |
Quick Reference Table
Use this table for quick conversions between kilowatt-hour and joules:
| kilowatt-hour | joules |
|---|---|
| 1 | 3,600,000 |
| 2 | 7,200,000 |
| 5 | 18,000,000 |
| 10 | 36,000,000 |
| 25 | 90,000,000 |
Frequently Asked Questions
How Many Joules in a Kilowatt-Hour?
There are 3,600,000 joules in one kilowatt-hour. One kilowatt-hour = 1,000 watts × 3,600 seconds = 3,600,000 joules (3.6 MJ). This is the exact conversion because watts (joules/second) × seconds = joules, and kWh = 1,000 W × 3,600 s. The joule is the SI unit of energy.
What is the formula to convert kilowatt-hour to joules?
The formula is: 1 kWh = 1,000 W × 3,600 s = 3,600,000 J. To convert, multiply the number of kilowatt-hours by 3,600,000 to get the equivalent in joules.
How do I convert joules to kilowatt-hour?
To convert joules to kilowatt-hour, divide the number of joules by 3,600,000. For example, 18,000,000 joules equals 5 kilowatt-hours.