Convert Foot-Pound-Force to Joules
Convert Foot-Pound-Force (ft·lbf) to Joules (J) instantly and accurately.
Conversion Formula
J = ft·lbf × 1.355817948
About Foot-Pound-Force
A foot-pound-force (ft·lbf) is the work done by one pound-force through one foot - exactly 1.3558179483314004 J. It is the standard torque and energy unit in US engineering. Automotive engine torque: Honda Civic ~125 lb-ft; Ford F-150 EcoBoost ~500 lb-ft. Muzzle energies: .22 LR ~140 ft·lbf; .308 Winchester ~2,600 ft·lbf; .50 BMG ~14,000 ft·lbf. Diesel pile hammers deliver 15,000-600,000 ft·lbf/blow. SAE Grade 8 bolts are specified at 7-950 ft·lbf. 1 ft·lbf = 12 in·lbf = 1.35582 J = 0.32405 cal.
About Joules
The joule (J) is the SI unit of energy, defined as one newton acting through one metre (1 J = 1 N·m = 1 kg·m²/s²). Named after James Prescott Joule, whose 1840s paddle-wheel experiments established the mechanical equivalent of heat (~4.15 J = 1 calorie). One joule is modest: it lifts a 100 g apple by 1 m, heats 0.239 mL of water by 1°C, or powers a 1 W LED for 1 second. Daily adult resting metabolism is ~6-9 MJ. 1 J = 1 W·s = 0.23901 cal = 9.4782 × 10⁻⁴ BTU = 2.7778 × 10⁻⁷ kWh.
Quick Reference Table
| Foot-Pound-Force (ft·lbf) | Joules (J) |
|---|---|
| 1 ft·lbf | 1.35582 J |
| 2 ft·lbf | 2.71164 J |
| 5 ft·lbf | 6.77909 J |
| 10 ft·lbf | 13.5582 J |
| 25 ft·lbf | 33.8954 J |
| 50 ft·lbf | 67.7909 J |
| 100 ft·lbf | 135.582 J |