Convert Foot-pounds to BTU
1 foot-pound (ft·lbf) equals 0.001285067463 British thermal units (BTU).
1 ft·lbf = 0.001285067463 BTU
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk foot-pound to BTU converter to paste a column from Excel.
How to Convert Foot-pound to BTU
- 1 ft·lbf = 0.001285067463 BTU
- 1 BTU = 778.1692623 ft·lbf
- Example: convert 15 ft·lbf to BTU: 15 ft·lbf = 15 × 0.001285067463 BTU = 0.01927601195 BTU
Reference conditions. BTU: International Table BTU (BTU_IT), 1055.05585262 J exactly.
Formula
BTU = ft·lbf × 0.001285067463457
or BTU = ft·lbf ÷ 778.169262266
Derivation from SI units:
- 1 ft·lbf = 0.3048 m × 4.4482216152605 N = 1.3558179483314 J
- 1 BTU_IT = 1055.05585262 J (exact)
- 1 ft·lbf = 1.355817948331 J ÷ 1055.05585262 J per BTU = 0.001285067463457 BTU
Both units are defined exactly, so the factor is exact. Foot-pound definition: foot-pound; BTU definition: British thermal unit.
Worked examples
- A reading of 25 ft·lbf converts to 0.03212668659 BTU.
25 ft·lbf × 0.001285067463 = 0.03212668659 BTU - A value of 250 ft·lbf is 0.3212668659 BTU.
250 ft·lbf × 0.001285067463 = 0.3212668659 BTU
Foot-pound to BTU conversion table
| Foot-pounds (ft·lbf) | BTU |
|---|---|
| 1 ft·lbf | 0.001285067463 BTU |
| 5 ft·lbf | 0.006425337317 BTU |
| 10 ft·lbf | 0.01285067463 BTU |
| 25 ft·lbf | 0.03212668659 BTU |
| 50 ft·lbf | 0.06425337317 BTU |
| 100 ft·lbf | 0.1285067463 BTU |
| 250 ft·lbf | 0.3212668659 BTU |
| 500 ft·lbf | 0.6425337317 BTU |
| 1000 ft·lbf | 1.285067463 BTU |
| 2000 ft·lbf | 2.570134927 BTU |
Where it's used
Foot-pounds are used for muzzle energy of firearms and air rifles, while British thermal units appear in furnace, boiler and fuel ratings in the US. Both measure energy, work and heat, so the conversion is a fixed factor.
Foot-pound to other energy units
| Conversion | 1 ft·lbf equals |
|---|---|
| foot-pound to joule | 1.355817948 J |
| foot-pound to kilojoule | 0.001355817948 kJ |
| foot-pound to megajoule | 0.000001355817948 MJ |
| foot-pound to calorie | 0.3240482668 cal |
| foot-pound to kilocalorie | 0.0003240482668 kcal |
| foot-pound to watt-hour | 0.0003766160968 Wh |
| foot-pound to kilowatt-hour | 3.766160968 × 10⁻⁷ kWh |
| foot-pound to BTU | 0.001285067463 BTU |
| foot-pound to therm | 1.285374295 × 10⁻⁸ thm |
| foot-pound to electronvolt | 8.462350028 × 10¹⁸ eV |
| foot-pound to erg | 13558179.48 erg |
Frequently asked questions
How many British thermal units are in 1 foot-pound?
1 ft·lbf = 0.001285067463 BTU.
How do I convert foot-pounds to British thermal units?
Multiply the value in ft·lbf by 0.001285067463, or divide it by 778.1692623. For example, 15 ft·lbf × 0.001285067463 = 0.01927601195 BTU.
Is the ft·lbf 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
- 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, "foot pound-force (ft·lbf)".
- 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 Foot-pounds to BTU. Retrieved October 17, 2026, from https://scientificconverters.com/energy/foot-pounds-to-btu/
IEEE
Scientific Converters, "Convert Foot-pounds to BTU," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/foot-pounds-to-btu/