Convert Joules to BTU
1 joule (J) equals 0.0009478171203 British thermal units (BTU).
1 J = 0.0009478171203 BTU
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk joule to BTU converter to paste a column from Excel.
How to Convert Joule to BTU
- 1 J = 0.0009478171203 BTU
- 1 BTU = 1055.055853 J
- Example: convert 15 J to BTU: 15 J = 15 × 0.0009478171203 BTU = 0.0142172568 BTU
Reference conditions. BTU: International Table BTU (BTU_IT), 1055.05585262 J exactly.
Formula
BTU = J × 0.0009478171203133
or BTU = J ÷ 1055.05585262
Derivation from SI units:
- 1 J = 1 N·m = 1 W·s = 1 kg·m²·s⁻²
- 1 BTU_IT = 1055.05585262 J (exact)
Both units are defined exactly, so the factor is exact. Joule definition: joule; BTU definition: British thermal unit.
Worked examples
- 1000 J (1 kJ) is 0.9478171203 BTU.
1000 J × 0.0009478171203 = 0.9478171203 BTU - 1000000 J (1 MJ) is 947.8171203 BTU.
1000000 J × 0.0009478171203 = 947.8171203 BTU
Joule to BTU conversion table
| Joules (J) | BTU |
|---|---|
| 1 J | 0.0009478171203 BTU |
| 10 J | 0.009478171203 BTU |
| 100 J | 0.09478171203 BTU |
| 250 J | 0.2369542801 BTU |
| 500 J | 0.4739085602 BTU |
| 1000 J | 0.9478171203 BTU |
| 4184 J | 3.965666831 BTU |
| 10000 J | 9.478171203 BTU |
| 100000 J | 94.78171203 BTU |
| 1000000 J | 947.8171203 BTU |
| 3600000 J | 3412.141633 BTU |
Where it's used
SI energy values are converted to BTU for US HVAC, boiler and fuel comparisons.
Joule to other energy units
| Conversion | 1 J equals |
|---|---|
| joule to kilojoule | 0.001 kJ |
| joule to megajoule | 0.000001 MJ |
| joule to calorie | 0.2390057361 cal |
| joule to kilocalorie | 0.0002390057361 kcal |
| joule to watt-hour | 0.0002777777778 Wh |
| joule to kilowatt-hour | 2.777777778 × 10⁻⁷ kWh |
| joule to BTU | 0.0009478171203 BTU |
| joule to therm | 9.48043428 × 10⁻⁹ thm |
| joule to electronvolt | 6.241509074 × 10¹⁸ eV |
| joule to foot-pound | 0.7375621493 ft·lbf |
| joule to erg | 10000000 erg |
Frequently asked questions
How many BTU is 1 kJ?
1 kJ = 0.947817 BTU.
How many British thermal units are in 1 joule?
1 J = 0.0009478171203 BTU.
How do I convert joules to British thermal units?
Multiply the value in J by 0.0009478171203, or divide it by 1055.055853. For example, 15 J × 0.0009478171203 = 0.0142172568 BTU.
Is the J to BTU 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
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4, coherent derived units with special names.
- 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)".
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 Joules to BTU. Retrieved October 17, 2026, from https://scientificconverters.com/energy/joules-to-btu/
IEEE
Scientific Converters, "Convert Joules to BTU," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/joules-to-btu/