Kilocalories to British Thermal Units
Type a value in either box to convert between kilocalories and British thermal units. The factor is 3.96567.
| Kilocalories | British Thermal Units |
|---|---|
| 1 kcal | 3.965667 BTU |
| 2 kcal | 7.931334 BTU |
| 3 kcal | 11.897 BTU |
| 5 kcal | 19.828334 BTU |
| 10 kcal | 39.656668 BTU |
| 25 kcal | 99.141671 BTU |
| 50 kcal | 198.283342 BTU |
| 100 kcal | 396.566683 BTU |
How to use
- Enter a value in the Kilocalories field.
- The British Thermal Units figure appears immediately — no button to press.
- Typing in the British Thermal Units field converts back to Kilocalories the same way.
- Use the reference table for the values that come up most often.
Kilocalories to British Thermal Units formula
To convert kilocalories to British thermal units, multiply by 3.96566683.
BTU = kcal × 3.96566683
Why this factor: the kilocalorie and the British thermal unit are both defined against the joule, so dividing one definition by the other gives 3.96566683 directly. Both definitions are set out in full below.
To go the other way, divide by 3.96566683 — or use the British Thermal Units to Kilocalories converter, which is the same calculation reversed.
Worked example
Given 2000 kcal, multiplying by 3.96566683 yields 7931.333663 BTU.
2000 kcal × 3.96566683 = 7931.333663 BTU
The converter above does this for any value you type, in either direction.
What is a kilocalorie?
A kilocalorie is 1,000 calories, and is what food labeling calls a 'Calorie'.
Definition: Exactly 4,184 joules.
Where it is used: Nutrition and dietary energy in the US and much of the world, and metabolic measurements.
Worth knowing: Written with a capital C ('Calorie') or as 'kcal' on labels. This is the unit meant by everyday talk about counting calories.
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.
Kilocalories vs British Thermal Units
The kilocalorie is a specialized 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 kilocalorie?
One kilocalorie equals 3.96566683 British thermal units.
What is the formula to convert kilocalories to British thermal units?
Multiply the number of kilocalories by 3.96566683. To reverse it, divide by 3.96566683 instead.
How do I convert British thermal units back to kilocalories?
Divide by 3.96566683, which is the same as multiplying by 0.252164401.
How many British thermal units are in 10 kilocalories?
10 kcal works out to 39.656668 BTU.
Is there anything to watch out for with kilocalories?
Written with a capital C ('Calorie') or as 'kcal' on labels. This is the unit meant by everyday talk about counting calories.
How is the kilocalorie defined?
Exactly 4,184 joules.