Foot-pound (ft·lbf)
The foot-pound (ft·lbf) is the work done by one pound-force over one foot, exactly 1.3558179483314004 J. As energy it is distinct from the torque unit pound-foot, although the factor is the same.
Symbol: ft·lbf (ASCII: ft-lbf)
Quantity: energy, work and heat
SI relation: 1 ft·lbf = 1.355817948331 J (exact)
Derivation: 1 ft·lbf = 0.3048 m × 4.4482216152605 N = 1.3558179483314 J
Exact: yes, by definition
Typical uses
- Muzzle energy of firearms and air rifles
- Impact test energy (Charpy)
- Mechanical work in US units
Convert foot-pounds to other units
| Conversion | 1 ft·lbf equals | Reverse |
|---|---|---|
| foot-pound to joule | 1.355817948 J | joule to foot-pound |
| foot-pound to kilojoule | 0.001355817948 kJ | kilojoule to foot-pound |
| foot-pound to kilocalorie | 0.0003240482668 kcal | kilocalorie to foot-pound |
| foot-pound to kilowatt-hour | 3.766160968 × 10⁻⁷ kWh | kilowatt-hour to foot-pound |
| foot-pound to BTU | 0.001285067463 BTU | BTU to foot-pound |
| foot-pound to megajoule | 0.000001355817948 MJ | megajoule to foot-pound |
| foot-pound to calorie | 0.3240482668 cal | calorie to foot-pound |
| foot-pound to watt-hour | 0.0003766160968 Wh | watt-hour to foot-pound |
| foot-pound to therm | 1.285374295 × 10⁻⁸ thm | therm to foot-pound |
| foot-pound to electronvolt | 8.462350028 × 10¹⁸ eV | electronvolt to foot-pound |
| foot-pound to erg | 13558179.48 erg | erg to foot-pound |
Open the Energy Converter to convert any value between all units.
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)".
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). Foot-pound (ft·lbf). Retrieved October 17, 2026, from https://scientificconverters.com/units/foot-pound-force/
IEEE
Scientific Converters, "Foot-pound (ft·lbf)," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/units/foot-pound-force/