Convert Foot-pound to Joule
1 foot-pound = 1.355818 joule (J). For example, 10 foot-pound = 13.55818 joule and 100 foot-pound = 135.5818 joule. Type any value below to convert foot-pound to joule both ways — it runs entirely in your browser.
Torque vs energy: Foot-pound (ft·lbf) is used both as a unit of ENERGY — where 1 N·m = 1 joule exactly — and as a unit of TORQUE (a twisting force × distance). This page converts the ENERGY meaning, so the figures above are correct for work and heat. A newton-metre of torque is a different physical quantity and does NOT convert into joules, kilowatt-hours or calories.
Quick answer: Foot-pound to Joule
1 Foot-pound = 1.355818 Joule (ft·lbf → J). To convert foot-pound to joule, multiply by 1.355818. To convert joule to foot-pound, multiply by 0.7375621. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common foot-pound-to-joule questions.
How to convert Foot-pound to Joule
To convert foot-pound to joule, multiply the number of foot-pound by the conversion factor 1.355818, because 1 ft·lbf = 1.355818 J. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 J = 0.7375621 ft·lbf, so you divide by 1.355818 (or multiply by 0.7375621) to turn joule back into foot-pound.
J = ft·lbf × 1.355818 ·
ft·lbf = J × 0.7375621
- Write down the value you want to convert, in foot-pound.
- Multiply it by 1.355818.
- The result is the same area/length/quantity expressed in joule.
Foot-pound to Joule — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 foot-pound is 6.77909 joule because 5 ft·lbf × 1.355818 = 6.77909 J.
| Foot-pound | Calculation | Joule |
|---|---|---|
| 1 ft·lbf | 1 ft·lbf × 1.355818 = 1.355818 J | 1.355818 J |
| 2 ft·lbf | 2 ft·lbf × 1.355818 = 2.711636 J | 2.711636 J |
| 3 ft·lbf | 3 ft·lbf × 1.355818 = 4.067454 J | 4.067454 J |
| 5 ft·lbf | 5 ft·lbf × 1.355818 = 6.77909 J | 6.77909 J |
| 7 ft·lbf | 7 ft·lbf × 1.355818 = 9.490726 J | 9.490726 J |
| 10 ft·lbf | 10 ft·lbf × 1.355818 = 13.55818 J | 13.55818 J |
| 12 ft·lbf | 12 ft·lbf × 1.355818 = 16.26982 J | 16.26982 J |
| 15 ft·lbf | 15 ft·lbf × 1.355818 = 20.33727 J | 20.33727 J |
| 20 ft·lbf | 20 ft·lbf × 1.355818 = 27.11636 J | 27.11636 J |
| 25 ft·lbf | 25 ft·lbf × 1.355818 = 33.89545 J | 33.89545 J |
| 50 ft·lbf | 50 ft·lbf × 1.355818 = 67.7909 J | 67.7909 J |
| 100 ft·lbf | 100 ft·lbf × 1.355818 = 135.5818 J | 135.5818 J |
Common Foot-pound to Joule conversions
These are the foot-pound-to-joule values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 foot-pound = 1.355818 joule
- 2 foot-pound = 2.711636 joule
- 2.5 foot-pound = 3.389545 joule
- 3 foot-pound = 4.067454 joule
- 4 foot-pound = 5.423272 joule
- 5 foot-pound = 6.77909 joule
- 6 foot-pound = 8.134908 joule
- 7 foot-pound = 9.490726 joule
- 8 foot-pound = 10.84654 joule
- 9 foot-pound = 12.20236 joule
- 10 foot-pound = 13.55818 joule
- 12 foot-pound = 16.26982 joule
- 15 foot-pound = 20.33727 joule
- 20 foot-pound = 27.11636 joule
- 25 foot-pound = 33.89545 joule
- 30 foot-pound = 40.67454 joule
- 50 foot-pound = 67.7909 joule
- 75 foot-pound = 101.6863 joule
- 100 foot-pound = 135.5818 joule
- 200 foot-pound = 271.1636 joule
- 500 foot-pound = 677.909 joule
- 1000 foot-pound = 1,355.818 joule
Foot-pound to Joule conversion chart (both directions)
The chart below converts foot-pound to joule and joule to foot-pound side by side, so it works whichever way you need. 1 foot-pound = 1.355818 joule, and 1 joule = 0.7375621 foot-pound.
| Foot-pound → Joule | Joule → Foot-pound |
|---|---|
| 0.25 ft·lbf = 0.3389545 J | 0.25 J = 0.1843905 ft·lbf |
| 0.5 ft·lbf = 0.677909 J | 0.5 J = 0.3687811 ft·lbf |
| 1 ft·lbf = 1.355818 J | 1 J = 0.7375621 ft·lbf |
| 2 ft·lbf = 2.711636 J | 2 J = 1.475124 ft·lbf |
| 3 ft·lbf = 4.067454 J | 3 J = 2.212686 ft·lbf |
| 4 ft·lbf = 5.423272 J | 4 J = 2.950249 ft·lbf |
| 5 ft·lbf = 6.77909 J | 5 J = 3.687811 ft·lbf |
| 6 ft·lbf = 8.134908 J | 6 J = 4.425373 ft·lbf |
| 7 ft·lbf = 9.490726 J | 7 J = 5.162935 ft·lbf |
| 8 ft·lbf = 10.84654 J | 8 J = 5.900497 ft·lbf |
| 9 ft·lbf = 12.20236 J | 9 J = 6.638059 ft·lbf |
| 10 ft·lbf = 13.55818 J | 10 J = 7.375621 ft·lbf |
| 12 ft·lbf = 16.26982 J | 12 J = 8.850746 ft·lbf |
| 15 ft·lbf = 20.33727 J | 15 J = 11.06343 ft·lbf |
| 20 ft·lbf = 27.11636 J | 20 J = 14.75124 ft·lbf |
| 25 ft·lbf = 33.89545 J | 25 J = 18.43905 ft·lbf |
| 30 ft·lbf = 40.67454 J | 30 J = 22.12686 ft·lbf |
| 40 ft·lbf = 54.23272 J | 40 J = 29.50249 ft·lbf |
| 50 ft·lbf = 67.7909 J | 50 J = 36.87811 ft·lbf |
| 75 ft·lbf = 101.6863 J | 75 J = 55.31716 ft·lbf |
| 100 ft·lbf = 135.5818 J | 100 J = 73.75621 ft·lbf |
| 150 ft·lbf = 203.3727 J | 150 J = 110.6343 ft·lbf |
| 200 ft·lbf = 271.1636 J | 200 J = 147.5124 ft·lbf |
| 250 ft·lbf = 338.9545 J | 250 J = 184.3905 ft·lbf |
| 500 ft·lbf = 677.909 J | 500 J = 368.7811 ft·lbf |
| 1000 ft·lbf = 1,355.818 J | 1000 J = 737.5621 ft·lbf |
Foot-pound vs Joule: which is bigger?
A foot-pound is the larger unit: one foot-pound equals 1.355818 joules. Put another way, you need 1.355818 joules to make a single foot-pound.
What is a Foot-pound? History, origin and usage
The foot-pound is a traditional British and American unit of work, defined as the energy transferred when one pound-force acts through a distance of one foot. It predates the metric joule and grew out of practical engineering in the imperial system, where force was measured in pounds-force and distance in feet.
The foot-pound survives in US engineering and especially in firearms ballistics, where the muzzle energy of a bullet is almost always quoted in foot-pounds. Its near-twin, the pound-foot (lbf·ft), is the everyday US unit of torque for engines and fasteners.
One foot-pound is about 1.356 joules — roughly the energy needed to lift a one-pound weight one foot. The foot-pound of energy and the pound-foot of torque carry the same number but describe different quantities, so careful writers add “of energy” or “of torque” to avoid confusion.
What is a Joule? History, origin and usage
The joule is named after the English physicist James Prescott Joule (1818-1889), a Salford brewer’s son who, through painstaking experiments in the 1840s, measured the mechanical equivalent of heat and showed that work and heat are interchangeable forms of energy. The name was proposed by Wilhelm Siemens at an 1882 British Association meeting, and the joule was adopted as an international unit at the 1889 International Electrical Congress — just weeks before Joule himself died.
As the SI unit of energy, the joule underpins all of physics and engineering, measuring mechanical work, heat and electrical energy alike (one joule is also one watt-second). It appears on European food labels (usually as kilojoules), in battery specifications, and anywhere energy must be stated in coherent SI units.
One joule is roughly the energy needed to lift a small apple (about 100 grams) one metre against gravity, or the kinetic energy of a 56-gram tennis ball travelling about 6 m/s. Because one joule equals one newton-metre, the joule is dimensionally identical to the newton-metre of torque, yet the two describe different physical quantities.
Convert 1 Foot-pound to other units
It can help to see a foot-pound next to the other units it is commonly compared with. One foot-pound (ft·lbf) is equal to:
| 1 Foot-pound equals | Unit |
|---|---|
| 1.355818 J | Joule |
| 1.355818 N·m | Newton-metre |
| 0.001355818 kJ | Kilojoule |
| 0.000001355818 MJ | Megajoule |
| 0.0003766161 Wh | Watt-hour |
| 0.0000003766161 kWh | Kilowatt-hour |
| 0.0000000003766161 MWh | Megawatt-hour |
| 8,462,350,000,000 MeV | Megaelectronvolt |
| 0.3240483 cal | Calorie |
| 0.0003240483 kcal | Kilocalorie |
| 0.001285067 BTU | British Thermal Unit |
Convert 1 Joule to other units
One joule (J) is equal to:
| 1 Joule equals | Unit |
|---|---|
| 1 N·m | Newton-metre |
| 0.001 kJ | Kilojoule |
| 0.000001 MJ | Megajoule |
| 0.0002777778 Wh | Watt-hour |
| 0.0000002777778 kWh | Kilowatt-hour |
| 0.0000000002777778 MWh | Megawatt-hour |
| 0.7375621 ft·lbf | Foot-pound |
| 6,241,509,000,000 MeV | Megaelectronvolt |
| 0.2390057 cal | Calorie |
| 0.0002390057 kcal | Kilocalorie |
| 0.0009478171 BTU | British Thermal Unit |
Tips for converting Foot-pound to Joule
- To go from foot-pound to joule, multiply by 1.355818; to go back, divide by 1.355818 (or multiply by 0.7375621).
- For a quick mental estimate, remember that 1 foot-pound ≈ 1.355818 joule, so 10 foot-pound ≈ 13.55818 joule.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type — change either side to convert in that direction.
How to use this Foot-pound to Joule converter
Type a number into the Foot-pound field and the equivalent in Joule appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Joule field to convert the other way (joule to foot-pound). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 ft·lbf = 1.355818 J), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for foot-pound-to-joule conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- NIST Special Publication 811 — Guide for the Use of the SI — publishes the exact metric equivalents of the customary units. The inch, foot, yard and mile are defined exactly in metres by the 1959 international yard-and-pound agreement, so every imperial figure on this page is exact, not rounded.
- BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
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Frequently asked questions
- How many joule are in 1 foot-pound?
- 1 foot-pound = 1.355818 joule (J). To convert any number of foot-pound to joule, multiply by 1.355818.
- How do I convert foot-pound to joule?
- Multiply the number of foot-pound by 1.355818. For example, 10 foot-pound = 10 × 1.355818 = 13.55818 joule, and 25 foot-pound = 33.89545 joule.
- How many foot-pound are in 1 joule?
- 1 joule = 0.7375621 foot-pound. So to convert joule back to foot-pound, multiply by 0.7375621.
- What is the formula to convert foot-pound to joule?
- joule = foot-pound × 1.355818. The reverse formula is foot-pound = joule × 0.7375621.
- How much is 100 foot-pound in joule?
- 100 foot-pound = 135.5818 joule. (And 1000 foot-pound = 1,355.818 joule.)
- Which is bigger, a foot-pound or a joule?
- A foot-pound is larger: 1 foot-pound = 1.355818 joule.
- Is this foot-pound to joule converter accurate?
- Yes — every value is computed from the exact 1.355818 J per ft·lbf factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert joule to foot-pound too?
- Yes. The converter works both ways — enter a value in either field. 1 joule = 0.7375621 foot-pound.