Convert BTU to Calories
1 British thermal unit (BTU) equals 252.1644007 calories (cal).
1 BTU = 252.1644007 cal
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk BTU to calorie converter to paste a column from Excel.
How to Convert BTU to Calorie
- 1 BTU = 252.1644007 cal
- 1 cal = 0.003965666831 BTU
- Example: convert 15 BTU to cal: 15 BTU = 15 × 252.1644007 cal = 3782.466011 cal
Reference conditions. BTU: International Table BTU (BTU_IT), 1055.05585262 J exactly. cal: Thermochemical calorie, 4.184 J exactly. The International Table calorie is 4.1868 J.
Formula
cal = BTU × 252.1644007218
Derivation from SI units:
- 1 BTU_IT = 1055.05585262 J (exact)
- 1 cal (thermochemical) = 4.184 J (exact)
- 1 BTU = 1055.05585262 J ÷ 4.184 J per cal = 252.1644007218 cal
Both units are defined exactly, so the factor is exact. BTU definition: British thermal unit; Calorie definition: calorie.
Worked examples
- A reading of 3412 BTU converts to 860384.9353 cal.
3412 BTU × 252.1644007 = 860384.9353 cal - A value of 24000 BTU is 6051945.617 cal.
24000 BTU × 252.1644007 = 6051945.617 cal
BTU to Calorie conversion table
| BTU | Calories (cal) |
|---|---|
| 1 BTU | 252.1644007 cal |
| 100 BTU | 25216.44007 cal |
| 1000 BTU | 252164.4007 cal |
| 3412 BTU | 860384.9353 cal |
| 5000 BTU | 1260822.004 cal |
| 10000 BTU | 2521644.007 cal |
| 12000 BTU | 3025972.809 cal |
| 24000 BTU | 6051945.617 cal |
| 50000 BTU | 12608220.04 cal |
| 100000 BTU | 25216440.07 cal |
| 1000000 BTU | 252164400.7 cal |
Where it's used
BTU are used for furnace, boiler and fuel ratings in the US, while calories appear in chemistry and calorimetry. 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 calories are in 1 British thermal unit?
1 BTU = 252.1644007 cal.
How do I convert British thermal units to calories?
Multiply the value in BTU by 252.1644007. For example, 15 BTU × 252.1644007 = 3782.466011 cal.
Is the BTU to cal 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)".
- 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, "calorie (thermochemical) (cal_th)".
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 Calories. Retrieved October 17, 2026, from https://scientificconverters.com/energy/btu-to-calories/
IEEE
Scientific Converters, "Convert BTU to Calories," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/btu-to-calories/