joules to kilojoules
Convert joule to kilojoule — instant, free, with the formula shown.
1 J=0.001 kJ
How to convert joule to kilojoule
To convert joule to kilojoule, multiply by 0.001:
kJ = J × 0.001
For example, 10 J × 0.001 = 0.01 kJ.
J to kJ conversion table
| joules (J) | kilojoules (kJ) |
|---|---|
| 1 J | 0.001 kJ |
| 2 J | 0.002 kJ |
| 5 J | 0.005 kJ |
| 10 J | 0.01 kJ |
| 25 J | 0.025 kJ |
| 50 J | 0.05 kJ |
| 100 J | 0.1 kJ |
| 250 J | 0.25 kJ |
| 500 J | 0.5 kJ |
| 1000 J | 1 kJ |
Other joule conversions
Convert to kilojoule from another unit
J to kJ — frequently asked
How many kilojoules are in 1 joule?
1 joule = 0.001 kilojoules (J × 0.001 = kJ).
What is the formula to convert joule to kilojoule?
Multiply your joule value by 0.001 to get kilojoule.
How do I convert 10 joules to kilojoules?
10 J = 0.01 kJ. For 100 J the answer is 0.1 kJ. Use the calculator on this page for any other value.
When to convert joule to kilojoule
1Electricity bills (kWh)
2Nutrition labels (kcal / food cal)
3HVAC and heating (BTU, therms)
4Physics and chemistry (J, eV)
Energy conversion — common questions
Is a food calorie the same as a calorie?
No — a food 'Calorie' (capital C) actually means 1 kilocalorie = 1,000 small calories = 4,184 J. Nutrition labels typically write 'cal' meaning kcal.
How many joules in 1 kWh?
1 kWh = 3,600,000 J (3.6 MJ). Because 1 kW × 1 hour = 1,000 W × 3,600 s = 3,600,000 J.
What is a BTU?
British Thermal Unit — the energy required to raise 1 pound of water by 1 °F. 1 BTU ≈ 1,055 J.
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