Convert Kilojoules to Watt-hours
Convert Kilojoules to Watt-hours instantly. 1 Kilojoule (kJ) equals 0.2778 Watt-hours (Wh).
Kilojoules to Watt-hours conversion table
| Kilojoules (kJ) | Watt-hours (Wh) |
|---|---|
| 1 kJ | 0.2778 Wh |
| 2 kJ | 0.5556 Wh |
| 3 kJ | 0.8333 Wh |
| 5 kJ | 1.3889 Wh |
| 10 kJ | 2.7778 Wh |
| 20 kJ | 5.5556 Wh |
| 50 kJ | 13.8889 Wh |
| 100 kJ | 27.7778 Wh |
| 500 kJ | 138.8889 Wh |
| 1,000 kJ | 277.7778 Wh |
1 Kilojoule = 0.2778 Watt-hours · multiply Kilojoules by 0.2778
About converting Kilojoules to Watt-hours
Kilojoules (kJ) and Watt-hours (Wh) are both units of energy, so converting between them is a single multiplication: multiply your Kilojoules figure by 0.2778. Ten Kilojoules comes to 2.7778 Watt-hours, and a hundred works out at 27.7778 Watt-hours.
Rule of thumb: going from Kilojoules to Watt-hours divides, so the figure always shrinks — it takes about 3.6 Kilojoules to make a single Watt-hour. If your answer came out bigger, you have the conversion the wrong way round.
What is a Kilojoule?
A kilojoule is a thousand joules, the size at which the joule becomes practical for everyday quantities. In Australia and New Zealand it is the primary unit on nutrition labels — food energy is quoted in kilojoules first, with calories relegated to a secondary figure or dropped entirely — so shoppers there think about daily intake in thousands of kilojoules rather than thousands of calories. It is also the working unit of chemistry, where reaction and bond energies are tabulated per mole. European labels print both kJ and kcal, which is why the same packet carries two different numbers for the same food.
What is a Watt-hour?
A watt-hour is energy, not power, and that distinction trips people up constantly. A watt is a rate — energy per second — so a watt-hour is what you get by sustaining that rate for an hour: a quantity of energy expressed as "this much power for this long". It is the natural unit for anything that stores energy and releases it gradually, which is why phone and laptop batteries are rated in watt-hours rather than the milliamp-hours stamped on the cell, and why airlines police lithium batteries by their watt-hour rating. Capacity in watt-hours tells you how long a load can run; watts alone never can.
To put both in perspective: a slice of bread carries roughly 300 kilojoules, while a phone battery holds somewhere around 15 watt-hours.
The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Watt-hours to Kilojoules converter, or browse all Energy converters.
Frequently asked questions
How many Watt-hours are in one Kilojoule?
There are 0.2778 Watt-hours in one Kilojoule.
How do I convert Kilojoules to Watt-hours?
Multiply the number of Kilojoules by 0.2778. For example, 10 Kilojoules = 2.7778 Watt-hours.
What is 100 Kilojoules in Watt-hours?
100 Kilojoules is equal to 27.7778 Watt-hours.
How do I convert Watt-hours to Kilojoules?
Multiply the Watt-hours value by 3.6 (or divide by 0.2778).
Is this Kilojoules to Watt-hours conversion exact?
The definition is exact — Kilojoules and Watt-hours are both fixed against the same base by international agreement — but the decimal shown here is rounded for readability, because the true ratio does not terminate. For engineering or scientific work, carry more decimal places than this page displays.
What is a Kilojoule?
A kilojoule is a thousand joules, the size at which the joule becomes practical for everyday quantities. In Australia and New Zealand it is the primary unit on nutrition labels — food energy is quoted in kilojoules first, with calories relegated to a secondary figure or dropped entirely — so shoppers there think about daily intake in thousands of kilojoules rather than thousands of calories. It is also the working unit of chemistry, where reaction and bond energies are tabulated per mole. European labels print both kJ and kcal, which is why the same packet carries two different numbers for the same food.
What is a Watt-hour?
A watt-hour is energy, not power, and that distinction trips people up constantly. A watt is a rate — energy per second — so a watt-hour is what you get by sustaining that rate for an hour: a quantity of energy expressed as "this much power for this long". It is the natural unit for anything that stores energy and releases it gradually, which is why phone and laptop batteries are rated in watt-hours rather than the milliamp-hours stamped on the cell, and why airlines police lithium batteries by their watt-hour rating. Capacity in watt-hours tells you how long a load can run; watts alone never can.