How to Convert British thermal units to Kilojoules (BTU to kJ)
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 kilojoules by hand, with examples and a quick-reference table.
The conversion
To convert british thermal units to kilojoules, multiply the value by 1.05505585. To go the other way, divide by the same number (or multiply by 0.9478171227). For a quick estimate, multiply by about 1.1.
Kilojoules = british thermal units × 1.05505585
Worked examples
- 3 BTU = 3.1652 kJ
- 12.5 BTU = 13.1882 kJ
- 75 BTU = 79.1292 kJ
British thermal units to Kilojoules table
| British thermal units | Kilojoules |
|---|---|
| 1 BTU | 1.0551 kJ |
| 2 BTU | 2.1101 kJ |
| 5 BTU | 5.2753 kJ |
| 10 BTU | 10.5506 kJ |
| 20 BTU | 21.1011 kJ |
| 25 BTU | 26.3764 kJ |
| 50 BTU | 52.7528 kJ |
| 100 BTU | 105.5056 kJ |
| 250 BTU | 263.764 kJ |
| 500 BTU | 527.5279 kJ |
| 1,000 BTU | 1,055.06 kJ |
Common questions
Is BTU to kJ 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 Kilojoules to British thermal units converter.
Mistakes to avoid
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.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Background
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.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
For any value, use the British thermal units to Kilojoules Converter or browse all energy converters.
Run your own numbers: British thermal units to Kilojoules Converter