Kilojoules to British Thermal Units
An instant kilojoules-to-British thermal units converter, with the formula and a reference table below.
| Kilojoules | British Thermal Units |
|---|---|
| 1 kJ | 0.947817 BTU |
| 2 kJ | 1.895634 BTU |
| 3 kJ | 2.843451 BTU |
| 5 kJ | 4.739086 BTU |
| 10 kJ | 9.478171 BTU |
| 25 kJ | 23.695428 BTU |
| 50 kJ | 47.390856 BTU |
| 100 kJ | 94.781712 BTU |
How to use
- Enter a value in the Kilojoules field.
- The British Thermal Units figure appears immediately — no button to press.
- Typing in the British Thermal Units field converts back to Kilojoules the same way.
- Use the reference table for the values that come up most often.
Kilojoules to British Thermal Units formula
To convert kilojoules to British thermal units, multiply by 0.94781712.
BTU = kJ × 0.94781712
Why this factor: the kilojoule and the British thermal unit are both defined against the joule, so dividing one definition by the other gives 0.94781712 directly. Both definitions are set out in full below.
To go the other way, divide by 0.94781712 — or use the British Thermal Units to Kilojoules converter, which is the same calculation reversed.
Worked example
Take 100 kJ and multiply by the factor 0.94781712: the result is 94.781712 BTU.
100 kJ × 0.94781712 = 94.781712 BTU
The converter above does this for any value you type, in either direction.
What is a kilojoule?
A kilojoule is 1,000 joules, the metric unit of food energy.
Definition: Exactly 1,000 joules.
Where it is used: Nutrition labels in Europe and Australia, and heating and cooling loads.
What is a British thermal unit?
A BTU is the energy needed to raise one pound of water by one degree Fahrenheit.
Definition: The international-table BTU is about 1,055.056 joules.
Where it is used: US heating and air-conditioning capacity ratings, natural gas pricing, and boiler output.
Worth knowing: Air-conditioner ratings quoted as 'BTU' are really BTU per hour — a rate of cooling, not a quantity of energy.
Kilojoules vs British Thermal Units
The kilojoule is a metric unit while the British thermal unit is a US customary unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many British thermal units are in a kilojoule?
One kilojoule equals 0.94781712 British thermal units.
What is the formula to convert kilojoules to British thermal units?
Multiply the number of kilojoules by 0.94781712. To reverse it, divide by 0.94781712 instead.
How do I convert British thermal units back to kilojoules?
Divide by 0.94781712, which is the same as multiplying by 1.05505585.
How many British thermal units are in 10 kilojoules?
10 kJ works out to 9.478171 BTU.
Is there anything to watch out for with British thermal units?
Air-conditioner ratings quoted as 'BTU' are really BTU per hour — a rate of cooling, not a quantity of energy.
How is the kilojoule defined?
Exactly 1,000 joules.