Gigajoules to Foot-pounds (GJ to ft⋅lbf)

1 gigajoule equals 737,562,149.3 foot-pounds (rounded).

1 gigajoule = 737,562,149.3 foot-pounds

How to convert gigajoules to foot-pounds

To convert gigajoules to foot-pounds, multiply the number of gigajoules by 737,562,149.3. The factor is rounded to 10 significant digits. To go the other way, multiply foot-pounds by 1.355817948×10⁻⁹ (rounded).

foot-pounds = gigajoules × 737,562,149.3

Example: 10 gigajoules = 7,375,621,493 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

Gigajoule (GJ)

Metric (SI)Current unit

One billion joules, roughly the energy in 29 liters of petrol. Used for natural gas and district heating.

One gigajoule is a billion joules, a size that only shows up when something large is being counted. An average lightning bolt carries about that much, and the superconducting magnet of the ATLAS experiment at CERN stores about 1.1 GJ of magnetic energy.

Everyday life can reach it too, just slowly. Filling a car with about 61 liters of gasoline, roughly 16 US gallons, puts in about 2 GJ of combustion energy. A standard refrigerator uses about 4.5 GJ in a year, and an average human heart muscle expends about 3.3 GJ over an 80-year lifetime.

Larger reference points sit nearby. One megawatt-hour is 3.6 GJ, exploding a ton of TNT releases about 4.2 GJ, and a barrel of oil equivalent is about 6.1 GJ. These comparisons explain why gigajoules suit annual household or building energy tallies better than joules or kilojoules.

1 gigajoule = 1,000,000,000 joules (exactly).

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

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.