British Thermal Units to Foot Pounds
Type a value in either box to convert between British thermal units and foot pounds. The factor is 778.169.
| British Thermal Units | Foot Pounds |
|---|---|
| 1 BTU | 778.169262 ft·lb |
| 2 BTU | 1556.338525 ft·lb |
| 3 BTU | 2334.507787 ft·lb |
| 5 BTU | 3890.846311 ft·lb |
| 10 BTU | 7781.692623 ft·lb |
| 25 BTU | 19454.231557 ft·lb |
| 50 BTU | 38908.463113 ft·lb |
| 100 BTU | 77816.926227 ft·lb |
How to use
- Enter a value in the British Thermal Units field.
- The Foot Pounds figure appears immediately — no button to press.
- Typing in the Foot Pounds field converts back to British Thermal Units the same way.
- Use the reference table for the values that come up most often.
British Thermal Units to Foot Pounds formula
Converting British thermal units to foot pounds is a single multiplication by 778.169262.
ft·lb = BTU × 778.169262
Why this factor: the British thermal unit and the foot-pound are both defined against the joule, so dividing one definition by the other gives 778.169262 directly. Both definitions are set out in full below.
To go the other way, divide by 778.169262 — or use the Foot Pounds to British Thermal Units converter, which is the same calculation reversed.
Worked example
Given 2000 BTU, multiplying by 778.169262 yields 1556338.524532 ft·lb.
2000 BTU × 778.169262 = 1556338.524532 ft·lb
The converter above does this for any value you type, in either direction.
What is a British thermal unit?
A BTU is the energy needed to raise one pound of water by one degree Fahrenheit.
Definition: The international-table BTU is about 1,055.056 joules.
Where it is used: US heating and air-conditioning capacity ratings, natural gas pricing, and boiler output.
Worth knowing: Air-conditioner ratings quoted as 'BTU' are really BTU per hour — a rate of cooling, not a quantity of energy.
What is a foot-pound?
A foot-pound is the work done by one pound-force acting through one foot.
Definition: About 1.3558179 joules.
Where it is used: US mechanical work and torque figures, fastener specifications, and firearm muzzle energy.
Worth knowing: As a torque unit it is properly 'pound-foot' (lbf·ft); as an energy unit it is 'foot-pound'. The numbers coincide but the quantities differ.
British Thermal Units vs Foot Pounds
The British thermal unit and the foot-pound belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many foot pounds are in a British thermal unit?
One British thermal unit equals 778.169262 foot pounds.
What is the formula to convert British thermal units to foot pounds?
Multiply the number of British thermal units by 778.169262. To reverse it, divide by 778.169262 instead.
How do I convert foot pounds back to British thermal units?
Divide by 778.169262, which is the same as multiplying by 0.00128506746.
How many foot pounds are in 10 British thermal units?
10 BTU works out to 7781.692623 ft·lb.
Is there anything to watch out for with British thermal units?
Air-conditioner ratings quoted as 'BTU' are really BTU per hour — a rate of cooling, not a quantity of energy.
How is the British thermal unit defined?
The international-table BTU is about 1,055.056 joules.