Liter-atmospheres to Kilojoules (L⋅atm to kJ)

1 liter-atmosphere equals 0.101325 kilojoules exactly.

1 liter-atmosphere = 0.101325 kilojoules

How to convert liter-atmospheres to kilojoules

To convert liter-atmospheres to kilojoules, multiply the number of liter-atmospheres by 0.101325. This factor is exact. To go the other way, multiply kilojoules by 9.869232667 (rounded).

kilojoules = liter-atmospheres × 0.101325

Example: 10 liter-atmospheres = 1.01325 kilojoules.

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

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)

Related conversions

See all energy units.