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Energy
Foot-pounds to BTU
Convert foot-pounds (ft·lb) to BTU (BTU). Type a value below to see the result update instantly. Reference table and formula included.
Calculator
1 ft·lb = 0.001285 BTU
Foot-pounds to BTU Conversion Table
Common values, ready to copy:
| foot-pounds | BTU |
|---|---|
| 1 ft·lb | 0.001285 BTU |
| 2 ft·lb | 0.00257 BTU |
| 5 ft·lb | 0.006425 BTU |
| 10 ft·lb | 0.012851 BTU |
| 25 ft·lb | 0.032127 BTU |
| 50 ft·lb | 0.064253 BTU |
| 100 ft·lb | 0.128506 BTU |
| 1,000 ft·lb | 1.2851 BTU |
Formula
BTU = foot-pounds × 1.28506436e-3
Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.
About Foot-pounds and BTU
Foot-pounds (ft·lb): The work done lifting one pound through one foot against gravity; 1 ft·lb = 1.35582 J. Common uses: Torque specifications in US automotive contexts (lug nuts, bolt torque), and some US engineering work.
BTU (BTU): British Thermal Unit; the energy to raise one pound of water by one degree Fahrenheit; defined as exactly 1,055.06 J. Common uses: US heating and air conditioning (a 24,000 BTU air conditioner cools roughly a 1,500 sq ft room), and US natural gas billing.
How the conversion works
Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.
The exact relationship is BTU = foot-pounds × 1.28506436e-3, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.
When this conversion matters
Converting between foot-pounds and BTU comes up wherever energy measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.