Convert British thermal units to calories
Converting British thermal units to calories is a common energy task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 BTU equals 252.164 cal, the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert British thermal units to calories
To convert British thermal units to calories, multiply the number of British thermal units by 252.164. For example, 10 BTU × 252.164 = 2,521.64 cal.
cal = BTU × 252.164
- Write down the value in British thermal units you want to convert.
- Multiply it by 252.164 (the exact BTU→cal factor).
- The result is your value in calories. Check it below with the converter or the table.
Conversion table
Common values of British thermal units and their equivalents in calories:
| BTU | cal |
|---|---|
| 1 | 252.164 |
| 2 | 504.329 |
| 3 | 756.493 |
| 4 | 1,008.66 |
| 5 | 1,260.82 |
| 10 | 2,521.64 |
| 20 | 5,043.29 |
| 25 | 6,304.11 |
| 50 | 12,608.2 |
| 100 | 25,216.4 |
| 250 | 63,041.1 |
| 500 | 126,082 |
About these units
British Thermal Unit (BTU). A British thermal unit is the energy to raise one pound of water by 1 °F, about 1,055 joules. Air conditioners, heaters and grills in the US are rated in BTU.
Calorie (cal). The small calorie is the energy needed to raise one gram of water by 1 °C, defined as exactly 4.184 joules. It is mostly used in chemistry and heat calculations.
Frequently asked questions
How do I convert British thermal units to calories?
To convert British thermal units to calories, multiply the number of British thermal units by 252.164. For example, 10 BTU × 252.164 = 2,521.64 cal. Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many calories are in 1 british thermal unit?
1 BTU = 252.164 cal. That is the fixed relationship used by this converter and by international standards.
How many British thermal units are in 1 calorie?
1 cal = 0.00396567 BTU. If you are converting in the opposite direction, use our Calorie to British Thermal Unit converter for the dedicated table and FAQ.
Is the British thermal units to calories conversion exact?
Yes. Both units are defined by international agreement, so the factor of 252.164 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is british thermal unit used for?
A British thermal unit is the energy to raise one pound of water by 1 °F, about 1,055 joules. Air conditioners, heaters and grills in the US are rated in BTU.