Megajoules to Foot-pounds (MJ to ft⋅lbf)

1 megajoule equals 737,562.1493 foot-pounds (rounded).

1 megajoule = 737,562.1493 foot-pounds

How to convert megajoules to foot-pounds

To convert megajoules to foot-pounds, multiply the number of megajoules by 737,562.1493. The factor is rounded to 10 significant digits. To go the other way, multiply foot-pounds by 0.000001355817948 (rounded).

foot-pounds = megajoules × 737,562.1493

Example: 10 megajoules = 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

Megajoule (MJ)

Metric (SI)Current unit

One million joules. Used for fuel energy content and natural gas billing in many countries.

Picture a one-tonne car moving at 44.7 m/s, about 100 miles per hour: its kinetic energy is roughly one megajoule. Because the joule was originally conceived in 1882 as 10 million ergs, a megajoule is 10 to the 13th ergs, a figure that shows how little the old CGS unit suited everyday work and why the joule won out.

Food provides a more familiar benchmark. A Snickers bar of 280 food calories holds about 1.2 MJ, and a day's 2,000 food calories for a moderately active woman come to about 8.4 MJ. A kilowatt-hour of electricity is exactly 3.6 MJ, and exploding a kilogram of TNT releases about 4.2 MJ.

In other words the megajoule sits at the scale of a single serving of fuel, food or electricity, which is why it turns up in energy-content tables where joules would give unwieldy numbers.

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

Sources: Wikipedia: Joule; Wikipedia: Orders of magnitude (energy); Wikipedia: Kilowatt-hour

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

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