Watt-hours to Liter-atmospheres (Wh to L⋅atm)

1 watt-hour equals 35.5292376 liter-atmospheres (rounded).

1 watt-hour = 35.5292376 liter-atmospheres

How to convert watt-hours to liter-atmospheres

To convert watt-hours to liter-atmospheres, multiply the number of watt-hours by 35.5292376. The factor is rounded to 10 significant digits. To go the other way, multiply liter-atmospheres by 0.02814583333 (rounded).

liter-atmospheres = watt-hours × 35.5292376

Example: 10 watt-hours = 355.292376 liter-atmospheres.

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

About these units

Watt-hour (Wh)

Metric (SI)Current unit

Exactly 3,600 joules, the energy used by a one-watt device in an hour. Battery capacities are quoted in watt-hours.

Pair a power unit with a unit of time and you get the watt-hour: one watt sustained for one hour, which works out to 3,600 joules. The watt itself was adopted at the second International Electrical Congress in 1889, in the same session that adopted the joule, so the two units share a birthday even though the watt-hour is the one people read off batteries.

Battery capacity is where it earns its keep. Multiplying amp-hours by the battery voltage gives an estimate of watt-hours, so a 2,500 mAh lithium-ion cell at 3.7 V holds roughly 9.25 Wh. That is why a 500 mA USB device runs about 3.7 hours on it rather than five: the cell voltage, not the 5 V from the port, sets the energy.

For scale, an alkaline AA battery holds about 9 kJ, which is 2.5 Wh. A 12 W LED lamp left on for an hour uses 12 Wh, and a 40 W appliance running for 25 hours uses 1,000 Wh.

1 watt-hour = 3,600 joules (exactly).

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

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

Related conversions

See all energy units.