The watt-hour
The watt-hour (Wh) equals 3,600 joules — the energy delivered by one watt of power over one hour. It is the natural unit for batteries, small electronics, and short-duration electrical loads.
Watt-hours to Joules Converter
1 Wh = 3600 J (watt-hour → joule)
1 Wh = 3600 J
1 watt-hour equals 3600 joules. To convert watt-hours to joules, multiply the watt-hour value by 3600. For quick reference: 1 Wh = 3600 J, 5 Wh = 18000 J, 10 Wh = 36000 J, 100 Wh = 360000 J.
Formula
Joules = Watt-hours × 3600Quick
When to use watt-hours → joules
Watt-hours to joules multiplies by 3600 (1 Wh = 1 W × 3600 s). A 60 Wh laptop battery stores 216 000 J = 216 kJ; a 2500 Wh power station holds 9 MJ. Watt-hours keep battery capacities readable at device scale, while joules are the SI unit that cancels cleanly against watts and seconds in physics. To estimate runtime, divide the watt-hour capacity by the load in watts — a 60 Wh battery powers a 15 W load for about four hours.
Small flywheel energy-storage demonstrations rated in watt-hours for their marketing spec need converting to joules to check against the rotational kinetic energy formula ½Iω² used in the underlying engineering design. A 5 Wh flywheel unit stores 18,000 J; a larger 25 Wh unit holds 90,000 J. Engineers validate a manufacturer's watt-hour claim by computing the joule figure independently from the flywheel's mass, radius, and spin speed, since the two numbers should match if the stated capacity is accurate rather than an optimistic rounding of test data.
How to convert watt-hours to joules
Take your value
Start with your value in watt-hours.
Multiply by 3600
Multiply the watt-hour value by 3600. This is the exact conversion factor from watt-hours to joules.
Read the result
The product is your value in joules. For example, 5 Wh × 3600 = 18000 J.
Conversion formula
The exact factor from watt-hours to joules is 3600.
Joules = Watt-hours × 3600
Watt-hours to Joules conversion table
Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.
| Watt-hours (Wh) | Joules (J) |
|---|---|
| 0.001 Wh | 3.6 J |
| 0.01 Wh | 36 J |
| 0.1 Wh | 360 J |
| 0.5 Wh | 1800 J |
| 1 Wh | 3600 J |
| 1.5 Wh | 5400 J |
| 2 Wh | 7200 J |
| 5 Wh | 18000 J |
| 10 Wh | 36000 J |
| 20 Wh | 72000 J |
| 50 Wh | 180000 J |
| 100 Wh | 360000 J |
| 200 Wh | 720000 J |
| 250 Wh | 900000 J |
| 500 Wh | 1800000 J |
| 1000 Wh | 3600000 J |
| 2000 Wh | 7200000 J |
| 2500 Wh | 9000000 J |
| 3600 Wh | 12960000 J |
| 5000 Wh | 18000000 J |
| 7500 Wh | 27000000 J |
| 10000 Wh | 36000000 J |
| 25000 Wh | 90000000 J |
| 50000 Wh | 180000000 J |
| 100000 Wh | 360000000 J |
| 250000 Wh | 900000000 J |
| 500000 Wh | 1800000000 J |
| 1000000 Wh | 3600000000 J |
| 2000000 Wh | 7200000000 J |
| 3600000 Wh | 12960000000 J |
| 5000000 Wh | 18000000000 J |
| 10000000 Wh | 36000000000 J |
| 25000000 Wh | 90000000000 J |
| 50000000 Wh | 180000000000 J |
| 100000000 Wh | 360000000000 J |
| 250000000 Wh | 900000000000 J |
| 500000000 Wh | 1800000000000 J |
| 1000000000 Wh | 3600000000000 J |
| 2000000000 Wh | 7200000000000 J |
| 5000000000 Wh | 18000000000000 J |
| 10000000000 Wh | 36000000000000 J |
| 20000000000 Wh | 72000000000000 J |
| 50000000000 Wh | 180000000000000 J |
| 100000000000 Wh | 360000000000000 J |
| 1000000000000 Wh | 3.6000 × 10^15 J |
| 10000000000000 Wh | 3.6000 × 10^16 J |
| 100000000000000 Wh | 3.6000 × 10^17 J |
| 1000000000000000 Wh | 3.6000 × 10^18 J |
| 10000000000000000 Wh | 3.6000 × 10^19 J |
| 100000000000000000 Wh | 3.6000 × 10^20 J |
Real-world reference
A typical smartphone battery stores about 15 Wh. An LED bulb uses 8 Wh per hour of operation. In joules, that gives you: 1 Wh = 3600 J, 10 Wh = 36000 J, 100 Wh = 360000 J.
Frequently asked questions
- How many joules are in 1 watt-hour?
- 1 watt-hour equals 3600 joules.
- How do I convert watt-hours to joules?
- Multiply the watt-hour value by 3600. So x Wh × 3600 = the equivalent in J.
- What is 5 watt-hours in joules?
- 5 watt-hours equals 18000 joules.
- What is 10 watt-hours in joules?
- 10 watt-hours equals 36000 joules.
- What is 100 watt-hours in joules?
- 100 watt-hours equals 360000 joules.
- How do I convert back from joules to watt-hours?
- Multiply the joule value by 0.000277778. For example, 1 J = 0.000277778 Wh.
- Is the watt-hour bigger than the joule?
- Yes. 1 watt-hour is larger than 1 joule — specifically 3600 times larger.
- Are these conversion factors exact?
- The factor is derived directly from the SI definitions of watt-hour and joule; the displayed value is rounded for readability, and the browser computes using IEEE 754 double-precision arithmetic.
About the watt-hour and the joule
The joule
The joule (J) is the SI derived unit of energy, work, and heat — defined as the energy transferred when a force of one newton acts over one meter. The joule is the standard unit in physics, chemistry, and most modern engineering documentation.