Energy Converter
Joule
Definition: The joule (symbol: J) is the base unit of energy in the International System of Units (SI). It is defined as the work done by a force of one newton acting through a distance of one meter.
History/origin: The unit is named in honor of the English physicist James Prescott Joule, who established the relationship between heat and mechanical work in the mid-19th century.
Current use: Joules are the standard unit used in physics and engineering to measure work, heat, and electrical energy.
Watt-hour
Definition: A watt-hour (symbol: Wh) is a unit of energy equivalent to one watt of power sustained for one hour. Since one watt is one joule per second, a watt-hour is exactly 3,600 joules.
History/origin: The watt-hour was derived from the unit of power (the watt, named after James Watt) to provide a practical measurement of energy consumption over time rather than instantaneous power.
Current use: Watt-hours are predominantly used to express the capacity of small batteries, such as those in smartphones, laptops, e-bikes, and portable power banks.
Joule to Watt-hour Conversion Table
| Joule [j] | Watt-hour [wh] |
|---|---|
| 0.01 j | 0.00000278 wh |
| 0.1 j | 0.00002778 wh |
| 1 j | 0.00027778 wh |
| 2 j | 0.00055556 wh |
| 3 j | 0.00083333 wh |
| 5 j | 0.00138889 wh |
| 10 j | 0.00277778 wh |
| 20 j | 0.00555556 wh |
| 50 j | 0.01388889 wh |
| 100 j | 0.02777778 wh |
| 1000 j | 0.27777778 wh |
How to Convert Joule to Watt-hour
1 j = 0.00027778 wh
1 wh = 3600 j
Example: convert 15 j to wh:
15 j = 15 × 0.00027778 wh = 0.00416667 wh
Did You Know?
- Did you know? One Joule is roughly the amount of energy required to lift a small apple (100 grams) one meter straight up into the air!
- Airline battery rules: If you travel with a power bank or laptop, the FAA limits the battery size to 100 Watt-hours (Wh) to prevent fire hazards in the cargo hold.