Convert BTU to Kilojoules
1 British thermal unit (BTU) equals 1.055055853 kilojoules (kJ).
1 BTU = 1.055055853 kJ
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk BTU to kilojoule converter to paste a column from Excel.
How to Convert BTU to Kilojoule
- 1 BTU = 1.055055853 kJ
- 1 kJ = 0.9478171203 BTU
- Example: convert 15 BTU to kJ: 15 BTU = 15 × 1.055055853 kJ = 15.82583779 kJ
Reference conditions. BTU: International Table BTU (BTU_IT), 1055.05585262 J exactly.
Formula
kJ = BTU × 1.05505585262
Derivation from SI units:
- 1 BTU_IT = 1055.05585262 J (exact)
- 1 kJ = 10³ J
- 1 BTU = 1055.05585262 J ÷ 1000 J per kJ = 1.05505585262 kJ
Both units are defined exactly, so the factor is exact. BTU definition: British thermal unit; Kilojoule definition: kilojoule.
Worked examples
- A reading of 3412 BTU converts to 3599.850569 kJ.
3412 BTU × 1.055055853 = 3599.850569 kJ - A value of 24000 BTU is 25321.34046 kJ.
24000 BTU × 1.055055853 = 25321.34046 kJ
BTU to Kilojoule conversion table
| BTU | Kilojoules (kJ) |
|---|---|
| 1 BTU | 1.055055853 kJ |
| 100 BTU | 105.5055853 kJ |
| 1000 BTU | 1055.055853 kJ |
| 3412 BTU | 3599.850569 kJ |
| 5000 BTU | 5275.279263 kJ |
| 10000 BTU | 10550.55853 kJ |
| 12000 BTU | 12660.67023 kJ |
| 24000 BTU | 25321.34046 kJ |
| 50000 BTU | 52752.79263 kJ |
| 100000 BTU | 105505.5853 kJ |
| 1000000 BTU | 1055055.853 kJ |
Where it's used
BTU are used for furnace, boiler and fuel ratings in the US, while kilojoules appear in nutrition labels (kJ per serving). Both measure energy, work and heat, so the conversion is a fixed factor.
BTU to other energy units
| Conversion | 1 BTU equals |
|---|---|
| BTU to joule | 1055.055853 J |
| BTU to kilojoule | 1.055055853 kJ |
| BTU to megajoule | 0.001055055853 MJ |
| BTU to calorie | 252.1644007 cal |
| BTU to kilocalorie | 0.2521644007 kcal |
| BTU to watt-hour | 0.2930710702 Wh |
| BTU to kilowatt-hour | 0.0002930710702 kWh |
| BTU to therm | 0.00001000238767 thm |
| BTU to electronvolt | 6.585140678 × 10²¹ eV |
| BTU to foot-pound | 778.1692623 ft·lbf |
| BTU to erg | 10550558530 erg |
Frequently asked questions
How many kilojoules are in 1 British thermal unit?
1 BTU = 1.055055853 kJ.
How do I convert British thermal units to kilojoules?
Multiply the value in BTU by 1.055055853. For example, 15 BTU × 1.055055853 = 15.82583779 kJ.
Is the BTU to kJ conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "British thermal unit_IT (Btu_IT)".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert BTU to Kilojoules. Retrieved October 17, 2026, from https://scientificconverters.com/energy/btu-to-kilojoules/
IEEE
Scientific Converters, "Convert BTU to Kilojoules," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/btu-to-kilojoules/