Kilojoules to Foot-pounds (kJ to ft⋅lbf)

1 kilojoule equals 737.5621493 foot-pounds (rounded).

1 kilojoule = 737.5621493 foot-pounds

How to convert kilojoules to foot-pounds

To convert kilojoules to foot-pounds, multiply the number of kilojoules by 737.5621493. The factor is rounded to 10 significant digits. To go the other way, multiply foot-pounds by 0.001355817948 (rounded).

foot-pounds = kilojoules × 737.5621493

Example: 10 kilojoules = 7,375.621493 foot-pounds.

The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.

About these units

Kilojoule (kJ)

Metric (SI)Current unit

1,000 joules. Food labels in many countries give energy in kilojoules.

Most food labels around the world express energy in kilojoules, which is the calorie's long retirement in action. The calorie came out of heat measurement, and the 1948 CGPM resolution stated that the joule should be preferred as the unit of heat. Labels that still show kilocalories alongside kilojoules rely on the thermochemical calorie of exactly 4.184 joules, so one kilocalorie is about 4.184 kJ.

The kilojoule is a convenient size for a body's daily bookkeeping. A person at rest uses about 5,000 kJ, or roughly 1,200 kcal, per day, and the recommended intake for a moderately active woman is given as 2,000 food calories, which is about 8,400 kJ.

Smaller physical comparisons land in the same range. One watt-hour is 3.6 kJ, a British thermal unit is about 1.1 kJ, exploding a gram of TNT releases about 4.2 kJ, and an alkaline AA battery holds about 9 kJ.

1 kilojoule = 1,000 joules (exactly).

Sources: Wikipedia: Kilojoule; Wikipedia: Joule; Wikipedia: Orders of magnitude (energy)

Foot-pound (ft⋅lbf)

US & ImperialCurrent unit

The work done by a force of one pound-force over one foot: about 1.35582 joules. Used for torque and energy in US engineering and ballistics.

Foot-pound hides a trap: the same words name two different things. As energy, a foot-pound is what a force of one pound-force transfers when it acts through a distance of one foot, about 1.355818 J. As torque, usually called the pound-foot, it is dimensionally the same but physically distinct, since energy is a scalar and torque is a vector, which is why careful writers specify foot-pound of energy or of torque.

The unit is tied to the early history of energy. In 1850 James Prescott Joule published a refined value of 772.692 foot-pounds of work per British thermal unit, which was the key figure in his demonstration that work converts to heat at a fixed rate. The same system defines the mechanical horsepower as 550 foot-pounds per second.

Today American ballistics is the best-known user. Muzzle energy of a bullet is commonly stated in foot-pounds, and a figure of about 7 kJ for an elephant gun, which is roughly 5,200 foot-pounds, shows the typical range for large rifle cartridges.

1 foot-pound = 1.355817948 joules (approximately).

Sources: Wikipedia: Foot-pound (energy); Wikipedia: James Prescott Joule; Wikipedia: Orders of magnitude (energy)

Related conversions

See all energy units.