British thermal unit.
BTU to Foot-pounds Converter — BTU to ft-lb
Convert BTU (BTU) to Foot-pound (ft-lb) using the exact conversion factor (1 btu = 778.1692623 foot-pound). See the formula, worked examples, conversion table, history, and common uses.
BTU to Foot-pounds converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Work from one pound-force over one foot.
Result = input x 1055.055853 / 1.355817948.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting BTU to Foot-pounds
BTU and Foot-pound both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. BTU is most often used for air conditioner and furnace capacity ratings in the us.
Formula
foot-pounds = btu × 778.169262266
This factor comes from each unit's defined relationship to the category's base unit: 1 btu equals 1055.05585262 base units, and 1 foot-pound equals 1.35581794833 base units, so dividing one by the other gives the direct btu-to-foot-pound factor of 778.169262266.
Simple example
1 BTU × 778.1692623 = 778.1692623 ft-lb
1 btu = 778.1692623 foot-pounds.
Real-world example
100 BTU × 778.1692623 = 77,816.92623 ft-lb
100 btu = 77,816.92623 foot-pounds.
Conversion table
| BTU (BTU) | Foot-pound (ft-lb) |
|---|---|
| 1 BTU | 778.1692623 ft-lb |
| 10 BTU | 7,781.692623 ft-lb |
| 50 BTU | 38,908.46311 ft-lb |
| 100 BTU | 77,816.92623 ft-lb |
| 500 BTU | 389,084.6311 ft-lb |
| 1,000 BTU | 778,169.2623 ft-lb |
Reverse conversion: Foot-pound to BTU
778.1692623 ft-lb × 0.001285067463 = 1 BTU
778.1692623 foot-pounds = 1 btu.
btu = foot-pounds × 0.00128506746346
For a page dedicated to this direction, see Foot-pound to BTU.
Understanding the BTU
BTU (BTU) measures energy. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). It is classified as a US customary unit.
Where it's used: United States (HVAC, heating, and appliance energy ratings)
Uses of the BTU today
- Air conditioner and furnace capacity ratings in the US
- Water heater and appliance energy specifications
- US energy industry (natural gas is often billed via BTU content)
History of the BTU
The BTU originated in 19th-century steam engineering as the heat needed to raise one pound of water by one degree Fahrenheit, paralleling the calorie's metric definition. Several slightly different BTU values existed historically before the 'International Table' BTU was standardized at exactly 1,055.05585262 joules.
Historical origin. BTU was not the invention of a single named person; it developed through the process described above.
Understanding the Foot-pound (ft-lb)
Work from one pound-force over one foot.
BTU — sources
- NIST Special Publication 811 — Documents the International Table BTU's exact joule equivalence.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many foot-pounds are in 1 btu?
1 btu equals 778.1692623 foot-pounds, using the exact defined conversion factor rather than an estimate.
How do I convert btu to foot-pound?
Multiply the btu value by 778.1692623. The converter above does this instantly to whatever precision you set.
How do I convert foot-pound back to btu?
Use the reverse factor: 1 foot-pound equals 0.0012850675 btu. You can also use the swap control in the converter above to flip the direction instantly.
What is a btu?
BTU (BTU) measures energy. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). It is classified as a US customary unit.
What is a foot-pound?
Foot-pound (ft-lb) is a unit of engineering.
Is the btu to foot-pound conversion exact?
Yes. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the btu still used today?
United States (HVAC, heating, and appliance energy ratings)
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.