Convert Foot-pounds to Kilojoules
1 foot-pound (ft·lbf) equals 0.001355817948 kilojoules (kJ).
1 ft·lbf = 0.001355817948 kJ
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk foot-pound to kilojoule converter to paste a column from Excel.
How to Convert Foot-pound to Kilojoule
- 1 ft·lbf = 0.001355817948 kJ
- 1 kJ = 737.5621493 ft·lbf
- Example: convert 15 ft·lbf to kJ: 15 ft·lbf = 15 × 0.001355817948 kJ = 0.02033726922 kJ
Formula
kJ = ft·lbf × 0.001355817948331
or kJ = ft·lbf ÷ 737.5621492773
Derivation from SI units:
- 1 ft·lbf = 0.3048 m × 4.4482216152605 N = 1.3558179483314 J
- 1 kJ = 10³ J
- 1 ft·lbf = 1.355817948331 J ÷ 1000 J per kJ = 0.001355817948331 kJ
Both units are defined exactly, so the factor is exact. Foot-pound definition: foot-pound; Kilojoule definition: kilojoule.
Worked examples
- A reading of 25 ft·lbf converts to 0.03389544871 kJ.
25 ft·lbf × 0.001355817948 = 0.03389544871 kJ - A value of 250 ft·lbf is 0.3389544871 kJ.
250 ft·lbf × 0.001355817948 = 0.3389544871 kJ
Foot-pound to Kilojoule conversion table
| Foot-pounds (ft·lbf) | Kilojoules (kJ) |
|---|---|
| 1 ft·lbf | 0.001355817948 kJ |
| 5 ft·lbf | 0.006779089742 kJ |
| 10 ft·lbf | 0.01355817948 kJ |
| 25 ft·lbf | 0.03389544871 kJ |
| 50 ft·lbf | 0.06779089742 kJ |
| 100 ft·lbf | 0.1355817948 kJ |
| 250 ft·lbf | 0.3389544871 kJ |
| 500 ft·lbf | 0.6779089742 kJ |
| 1000 ft·lbf | 1.355817948 kJ |
| 2000 ft·lbf | 2.711635897 kJ |
Where it's used
Foot-pounds are used for muzzle energy of firearms and air rifles, while kilojoules appear in nutrition labels (kJ per serving). 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 kilojoules are in 1 foot-pound?
1 ft·lbf = 0.001355817948 kJ.
How do I convert foot-pounds to kilojoules?
Multiply the value in ft·lbf by 0.001355817948, or divide it by 737.5621493. For example, 15 ft·lbf × 0.001355817948 = 0.02033726922 kJ.
Is the ft·lbf 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, "foot pound-force (ft·lbf)".
- 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 Foot-pounds to Kilojoules. Retrieved October 17, 2026, from https://scientificconverters.com/energy/foot-pounds-to-kilojoules/
IEEE
Scientific Converters, "Convert Foot-pounds to Kilojoules," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/energy/foot-pounds-to-kilojoules/