Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
British thermal units to Kilojoules
Convert BTU to kJ instantly, then review the formula, assumptions, and rounding guidance.
Thermal unitsInstant result
Decimals
Formula result = input × 1055.055853 ÷ 1000. 1 BTU = 1.0551 kJ
Common examples
One value, several units
Joules1,055.0559 J
Kilojoules1.0551 kJ
Calories252.1644 cal
Kilocalories0.2522 kcal
Therms0 thm
Conversion table
| BTU | kJ |
|---|---|
| 1 BTU | 1.0551 kJ |
| 2 BTU | 2.1101 kJ |
| 5 BTU | 5.2753 kJ |
| 10 BTU | 10.5506 kJ |
| 25 BTU | 26.3764 kJ |
| 50 BTU | 52.7528 kJ |
| 100 BTU | 105.5056 kJ |
Conversion chart
1 BTU1.0551 kJ
5 BTU5.2753 kJ
10 BTU10.5506 kJ
25 BTU26.3764 kJ
50 BTU52.7528 kJ
Worked example
1 BTU is approximately 1,055.06 joules.
Unit definition
British thermal units (BTU) One british thermal units equals 1,055.055853 joule.
Unit history
British thermal units is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert BTU to joule.
3. Convert the base value to kJ and apply your display precision.
Understand the result before using it
British thermal units to Kilojoules converts a value measured in British thermal units (BTU) into the equivalent value in Kilojoules (kJ). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 1055.055853 ÷ 1000
Assumptions
- British thermal units and Kilojoules represent the same thermal units quantity.
- The input is expressed in BTU; the output is expressed in kJ.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 BTU = 1.055055853 kJ. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a BTU measurement in a document that expects kJ.
- Compare a british thermal units value with a value reported in kilojoules.
- Check the BTU-to-kJ arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Do not confuse BTU with another unit that has a similar name or symbol.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert British thermal units to Kilojoules?
result = input × 1055.055853 ÷ 1000 Using the displayed relationship, 1 BTU equals 1.055055853 kJ.
How many Kilojoules are in one British thermal units?
One British thermal units is 1.055055853 Kilojoules. The displayed digits may be rounded.
Can I reverse the BTU to kJ conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts kJ back to BTU.
Is the British thermal units to Kilojoules result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.