Convert Foot-pounds to Joules
1 foot-pound is 1.355818 J. One foot-pound is exactly 1.35581794833 joules.
One foot-pound is 1.3558179 joules. To convert foot-pounds to joules, multiply by 1.3558179; to go the other way, divide by 1.3558179 or multiply by 0.73756215. The factor is exact rather than rounded: it follows from NIST Special Publication 811. A pound-force acting through one foot.
Factor checked against the defining standard · How we check
- Foot-pounds × 1.3558179
value * 1.355817948331.356 J
1 foot-pound in every energy unit
| Unit | Value | Exact factor |
|---|---|---|
| joules | 1.355817948 J | × 1.35581794833 |
| kilojoules | 0.001355817948 kJ | × 0.00135581794833 |
| calories | 0.3240482668 cal | × 0.32404826681 |
| kilocalories | 0.0003240482668 kcal | × 0.00032404826681 |
| watt-hours | 0.0003766160968 Wh | × 0.000376616096759 |
| kilowatt-hours | 0.0000003766160968 kWh | × 0.000000376616096759 |
| British thermal units | 0.001285067463 BTU | × 0.00128506746346 |
| foot-pounds (as entered) | 1 ft·lbf | — |
Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert foot-pounds to joules?
- 1.Take the measurement in foot-pounds.
- 2.Multiply by 1.3558179 — that is how many joules fit in one foot-pound.
- 3.To go back the other way, divide by 1.3558179, or multiply by 0.73756215.
Worked example: 25 foot-pounds to joules
- Formula
- ft·lbf × 1.3558179 = J
- Arithmetic
- 25 × 1.3558179 = 33.895449 J
- Answer
- 25 ft·lbf = 33.895449 J
The factor is rounded for display; the figure above is computed from the full value.
Foot-pounds to joules conversion table
| Foot-pounds | Joules |
|---|---|
| 1 ft·lbf | 1.355818 J |
| 2 ft·lbf | 2.711636 J |
| 3 ft·lbf | 4.067454 J |
| 4 ft·lbf | 5.423272 J |
| 5 ft·lbf | 6.77909 J |
| 6 ft·lbf | 8.134908 J |
| 7 ft·lbf | 9.490726 J |
| 8 ft·lbf | 10.846544 J |
| 9 ft·lbf | 12.202362 J |
| 10 ft·lbf | 13.558179 J |
| 12 ft·lbf | 16.269815 J |
| 15 ft·lbf | 20.337269 J |
| 20 ft·lbf | 27.116359 J |
| 25 ft·lbf | 33.895449 J |
| 50 ft·lbf | 67.790897 J |
| 100 ft·lbf | 135.581795 J |
| 200 ft·lbf | 271.16359 J |
| 300 ft·lbf | 406.745384 J |
| 500 ft·lbf | 677.908974 J |
| 1000 ft·lbf | 1,355.817948 J |
| 2000 ft·lbf | 2,711.635897 J |
| 5000 ft·lbf | 6,779.089742 J |
| 10000 ft·lbf | 13,558.179483 J |
What is a foot-pound?
A pound-force acting through one foot. The same arithmetic as the torque unit of that name, and a different quantity: this one is work done, not twist applied.
What is a joule?
The SI unit: one newton acting through one metre. Dropping a small apple one metre releases about one joule.
How many joules are in a foot-pound?
One foot-pound is 1.3558179 joules. Going the other way, one joule is 0.73756215 foot-pounds. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every energy unit here
| Unit | Symbol | One of these is |
|---|---|---|
| Joules | J | the base unit |
| Kilojoules | kJ | 1000 joule |
| Calories | cal | 4.184 joule |
| Kilocalories | kcal | 4184 joule |
| Watt-hours | Wh | 3600 joule |
| Kilowatt-hours | kWh | 3600000 joule |
| British thermal units | BTU | 1055.0559 joule |
| Foot-pounds | ft·lbf | 1.3558179 joule |
Source: NIST Special Publication 811 — the thermochemical calorie is exactly 4.184 J
Questions people actually ask
- How many joules are in a foot-pound?
- 1.3558179. The SI unit: one newton acting through one metre. Dropping a small apple one metre releases about one joule.
- How do I convert joules back to foot-pounds?
- Divide by 1.3558179, or multiply by 0.73756215 — they are the same operation.
Other energy conversions
Joules to foot-pounds — the same conversion the other way.