Convert Kilojoules to Joules
Convert Kilojoules to Joules instantly. 1 Kilojoule (kJ) equals 1,000 Joules (J).
Kilojoules to Joules conversion table
| Kilojoules (kJ) | Joules (J) |
|---|---|
| 1 kJ | 1,000 J |
| 2 kJ | 2,000 J |
| 3 kJ | 3,000 J |
| 5 kJ | 5,000 J |
| 10 kJ | 10,000 J |
| 20 kJ | 20,000 J |
| 50 kJ | 50,000 J |
| 100 kJ | 100,000 J |
| 500 kJ | 500,000 J |
| 1,000 kJ | 1,000,000 J |
1 Kilojoule = 1,000 Joules · multiply Kilojoules by 1,000
About converting Kilojoules to Joules
Kilojoules (kJ) and Joules (J) are both units of energy, so converting between them is a single multiplication: multiply your Kilojoules figure by 1,000. Ten Kilojoules comes to 10,000 Joules, and a hundred works out at 100,000 Joules.
Rule of thumb: going from Kilojoules to Joules multiplies, so the figure always grows — one Kilojoule is already 1,000 Joules. If your answer came out smaller, 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 Joule?
The joule is the SI unit of energy and the reference every other energy unit here is defined against. One joule is one newton acting over one metre — push with a newton of force, move a metre, and you have spent a joule. It is named after James Prescott Joule, whose painstaking experiments established that heat and mechanical work are the same thing, measurable in the same units. That result sounds obvious now and was foundational then: it collapsed heat, motion and work into a single quantity called energy, which is why one unit can serve food, electricity, explosives and engines alike.
To put both in perspective: a slice of bread carries roughly 300 kilojoules, while lifting an apple one metre takes about a joule.
The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Joules to Kilojoules converter, or browse all Energy converters.
Frequently asked questions
How many Joules are in one Kilojoule?
There are 1,000 Joules in one Kilojoule.
How do I convert Kilojoules to Joules?
Multiply the number of Kilojoules by 1,000. For example, 10 Kilojoules = 10,000 Joules.
What is 100 Kilojoules in Joules?
100 Kilojoules is equal to 100,000 Joules.
How do I convert Joules to Kilojoules?
Multiply the Joules value by 0.001 (or divide by 1,000).
Is this Kilojoules to Joules conversion exact?
Yes, exactly. Both units are fixed against the same base by definition, and 1 Kilojoule = 1,000 Joules is the complete value — nothing is rounded away.
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 Joule?
The joule is the SI unit of energy and the reference every other energy unit here is defined against. One joule is one newton acting over one metre — push with a newton of force, move a metre, and you have spent a joule. It is named after James Prescott Joule, whose painstaking experiments established that heat and mechanical work are the same thing, measurable in the same units. That result sounds obvious now and was foundational then: it collapsed heat, motion and work into a single quantity called energy, which is why one unit can serve food, electricity, explosives and engines alike.