How to Convert British thermal units to Calories (BTU to cal)
Energy conversions link food labels in kJ and kcal, SP Group bills in kWh and air-conditioner capacity in BTU. This guide shows how to convert british thermal units into calories by hand, with examples and a quick-reference table.
The conversion
To convert british thermal units to calories, multiply the value by 252.1644000956. To go the other way, divide by the same number (or multiply by 0.0039656668). For a quick estimate, multiply by about 250.
Calories = british thermal units × 252.1644000956
Worked examples
- 3 BTU = 756.4932 cal
- 12.5 BTU = 3,152.06 cal
- 75 BTU = 18,912.33 cal
British thermal units to Calories table
| British thermal units | Calories |
|---|---|
| 1 BTU | 252.1644 cal |
| 2 BTU | 504.3288 cal |
| 5 BTU | 1,260.82 cal |
| 10 BTU | 2,521.64 cal |
| 20 BTU | 5,043.29 cal |
| 25 BTU | 6,304.11 cal |
| 50 BTU | 12,608.22 cal |
| 100 BTU | 25,216.44 cal |
| 250 BTU | 63,041.1 cal |
| 500 BTU | 126,082.2 cal |
| 1,000 BTU | 252,164.4 cal |
Common questions
Is BTU to cal exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Calories to British thermal units converter.
Mistakes to avoid
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Background
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
For any value, use the British thermal units to Calories Converter or browse all energy converters.
Run your own numbers: British thermal units to Calories Converter