Foot-Pound Force (ft·lbf) to BTU (IT) Converter
Enter a value to instantly convert between energy units.
1 Foot-Pound Force = 0.0013 BTU (IT)
Key Formulas
Kilocalorie → Kilojoule
kJ = kcal × 4.184Kilojoule → Kilocalorie
kcal = kJ × 0.239006Kilowatt-Hour → Joule
J = kWh × 3600000Joule → Kilowatt-Hour
kWh = J × 2.77778e-7Formula
BTU = ft·lbf × 0.001285067One foot-pound force equals 0.00129 BTU. Foot-pound force (ft·lbf) is the imperial mechanical energy unit used in US engineering for torque, work, and machinery specifications. BTU is the thermal energy unit. Converting ft·lbf to BTU is useful when analyzing mechanical systems that generate heat (friction, motor efficiency) or comparing mechanical work to thermal output — for example, engine brake horsepower converted to heating effect.
Source: NIST SP 811, Table B.8
Frequently Asked Questions
Real-World Examples
The mechanical equivalent of heat: 778.169 ft·lbf = exactly 1 BTU — foundational constant in thermodynamics.
778.169 ft·lbf = 1 BTU
An electric motor produces 5,000 ft·lbf of torque continuously — equivalent to 6.4 BTU/s of mechanical work.
5000 ft·lbf = 6.425 BTU
A hand tool (wrench) applies 100 ft·lbf of torque — 0.129 BTU — negligible thermal output for brief use.
100 ft·lbf = 0.1285 BTU
An industrial pump does 50,000 ft·lbf of work per cycle — 64.3 BTU — converted to thermal energy if all work is dissipated.
50000 ft·lbf = 64.25 BTU