British thermal units to calories
Type a value in British thermal units to see it in calories straight away, or type in the second box to convert back.
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How to use it
- Type the value in the British thermal units box.
- Read the result in calories as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
cal = BTU × 252.1644007
Multiply the value in British thermal units by 252.1644007 to get calories.
Example
To convert 25 BTU to calories: 25 × 252.1644007 = 6,304.11 cal.
Conversion table
| British thermal units (BTU) | Calories (cal) |
|---|---|
| 1 | 252.164 |
| 2 | 504.329 |
| 3 | 756.493 |
| 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 |
| 1,000 | 252,164 |
About the units
- British thermal unit
- The imperial unit of heat, using the International Table definition of exactly 1055.05585262 joules. Seen in air conditioner and heater ratings.
- Calorie
- The small calorie in its thermochemical definition, exactly 4.184 joules. The food calorie on labels equals 1000 of these.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many calories are in one British thermal unit?
1 BTU = 252.164 cal exactly.
How do I convert British thermal units to calories?
Use cal = BTU × 252.1644007. For example, 25 BTU = 6,304.11 cal.
How many British thermal units are in one calorie?
1 cal = 0.00396567 BTU.
Which calorie do these converters use?
The thermochemical calorie, exactly 4.184 joules, the factor many countries use to turn kcal into kJ on food labels. The International Table calorie is 4.1868 joules, less than 0.07% larger.
What is the difference between kW and kWh?
A kilowatt is a unit of power, the rate of using energy, while a kilowatt-hour is an amount of energy. A 2 kW heater running for three hours uses 6 kWh.