How many BTU is 1 foot-pound?

1 foot-pound-force (ft·lbf) equals approximately 0.00128507 BTU (IT). This comes from the mechanical equivalent of heat: 1 ft·lbf = 1.35582 J and 1 BTU = 1055.05585 J, so 1.35582 / 1055.05585 ≈ 0.00128507 BTU.

How do I convert foot-pounds to BTU manually?

Multiply the foot-pound value by 0.00128507. For example, 778.169 ft·lbf × 0.00128507 ≈ 1.000 BTU. To convert BTU back to foot-pounds, multiply by 778.16926 (or divide by 0.00128507).

What is the difference between a foot-pound and a BTU?

Both measure energy, but from different origins. The foot-pound (ft·lbf) is a mechanical unit — the work done by one pound-force over one foot of displacement. The BTU (British Thermal Unit) is a thermal unit — the energy needed to raise one pound of water by 1 °F. They are linked through the mechanical equivalent of heat established by James Prescott Joule.

What is the mechanical equivalent of heat?

The mechanical equivalent of heat is the numerical relationship between mechanical work and thermal energy. Joule showed in the 19th century that 1 BTU ≈ 778.16926 ft·lbf, meaning that much mechanical work is required to produce the heat equivalent of one BTU. This equivalence underpins the first law of thermodynamics.

When would I need to convert foot-pounds to BTU?

This conversion appears in mechanical engineering and physics whenever energy is specified in mechanical units (ft·lbf) but needs to be compared against thermal quantities (BTU). Common contexts include firearms ballistics, steam-engine efficiency, HVAC analysis, and thermodynamics coursework.

Is foot-pound the same as pound-foot?

No, though the numbers are equal in magnitude. Foot-pound (ft·lbf) is a unit of energy or work. Pound-foot (lb·ft) is a unit of torque. They are dimensionally different quantities; do not interchange them in engineering calculations.

Foot Pounds to BTU Converter

Name: Foot Pounds to BTU Converter
Availability: InStock
Author: Nham Vu

Enter a value in foot-pounds and instantly see the BTU equivalent, with reverse conversion and a common-value reference table.

Converter

Energy in Foot-Pounds (ft·lbf)

= 1 BTU

Energy in BTU (British Thermal Units)

= 778.16926 ft·lbf

Reference Table

ft·lbf	BTU
1	0.00128507
10	0.0128507
100	0.128507
500	0.642534
778.169	1.000
1,000	1.28507
5,000	6.4254
10,000	12.8507
100,000	128.507
1,000,000	1,285.07

1 ft·lbf = 0.00128507 BTU (IT). Based on 1 ft·lbf = 1.35582 J and 1 BTU = 1055.05585 J.

Summary

Enter a value in foot-pounds and instantly see the BTU equivalent, with reverse conversion and a common-value reference table.

How it works

Enter an energy value in foot-pounds in the top input field.
The BTU result appears instantly — no button press needed.
Use the reverse field to convert BTU back to foot-pounds.
Click "Copy" next to any result to copy the value to your clipboard.
Check the reference table for common foot-pound-to-BTU values at a glance.

Use cases

Convert firearm or ballistic muzzle energy from ft·lbf to BTU for thermodynamic analysis.
Translate mechanical work values in engineering reports from foot-pounds to BTU heat equivalents.
Cross-check steam engine or combustion efficiency data that mixes mechanical and thermal units.
Convert torque or impact energy measurements in ft·lbf to BTU for heat-transfer calculations.
Verify thermodynamic cycle energy balances that involve both mechanical and thermal units.
Compare historical physics textbook values given in ft·lbf against modern BTU references.
Convert kinetic energy measurements from ft·lbf to BTU in automotive crash-test analysis.
Translate mechanical equivalent of heat problems from foot-pounds into BTU for homework or exams.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu