Liter-atmospheres to Joules (L⋅atm to J)

1 liter-atmosphere equals 101.325 joules exactly.

1 liter-atmosphere = 101.325 joules

How to convert liter-atmospheres to joules

To convert liter-atmospheres to joules, multiply the number of liter-atmospheres by 101.325. This factor is exact. To go the other way, multiply joules by 0.009869232667 (rounded).

joules = liter-atmospheres × 101.325

Example: 10 liter-atmospheres = 1,013.25 joules.

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

About these units

Liter-atmosphere (L⋅atm)

ScientificTraditional unit (still used in some regions)

Exactly 101.325 joules, the work of expanding a gas by one liter against one standard atmosphere.

Pressure times volume has the dimensions of energy, which is why gas chemists found it convenient to multiply a pressure in atmospheres by a volume in litres. One litre-atmosphere is 1 atm acting over 1 L, and the figure used here is 101.325 J. The arithmetic is simple: the standard atmosphere is 101,325 Pa, and a litre is 0.001 cubic metre, so the product is 101.325 pascal-cubic-metres, which is joules.

The atmosphere in this definition goes back to the barometer, being first set by a 760 mm column of mercury at 0 degrees Celsius. The tenth General Conference on Weights and Measures in 1954 fixed it as exactly 1,013,250 dynes per square centimetre, with no dependence on any substance. In 1982 IUPAC moved its reference pressure for substance data to 100 kPa. Expressed in thermochemical calories, one litre-atmosphere is about 24.2 cal.

1 liter-atmosphere = 101.325 joules (exactly).

Sources: Wikipedia: Conversion of units of energy; Wikipedia: Atmosphere (unit); Wikipedia: Calorie

Joule (J)

Metric (SI)Current unit

The SI unit of energy: the work done by a force of one newton over one meter, or one watt for one second.

James Prescott Joule was born in Salford on 24 December 1818, the son of a wealthy brewer, and later ran the family brewery while treating science as a serious hobby. In June 1845 he told a British Association meeting in Cambridge about his best-known experiment: a falling weight turned a paddle wheel inside an insulated barrel of water, and the water warmed up. Mechanical work turned into heat at a fixed rate, which supported energy conservation and undermined the caloric theory of heat.

The unit came later. On 23 August 1882 Carl Wilhelm Siemens proposed at a British Association meeting that a unit of heat equal to 10 million ergs be named the joule, and in 1889 the second International Electrical Congress adopted it alongside the watt. Joule died that same year. In 1948 the CGPM added that the joule should be preferred to the calorie as the unit of heat, and it entered the SI in 1960.

For scale, one joule is about the energy needed to lift an apple of roughly 102 g by one meter. A 56 g tennis ball moving at 6 m/s carries about one joule of kinetic energy.

The joule is the reference unit for energy on this site.

Sources: Wikipedia: Joule; Wikipedia: James Prescott Joule

Related conversions

See all energy units.