Watt-hours to Tonnes Of Oil Equivalent (Wh to toe)

1 watt-hour equals 8.598452279×10⁻⁸ tonnes of oil equivalent (rounded).

1 watt-hour = 8.598452279×10⁻⁸ tonnes of oil equivalent

How to convert watt-hours to tonnes of oil equivalent

To convert watt-hours to tonnes of oil equivalent, multiply the number of watt-hours by 8.598452279×10⁻⁸. The factor is rounded to 10 significant digits. To go the other way, multiply tonnes of oil equivalent by 11,630,000.

tonnes of oil equivalent = watt-hours × 8.598452279×10⁻⁸

Example: 10 watt-hours = 8.598452279×10⁻⁷ tonnes of oil equivalent.

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)

Tonne Of Oil Equivalent (toe)

Metric (SI)Current unit

Exactly 41.868 GJ, the energy released by burning one tonne of crude oil. A standard unit in energy statistics.

Energy statisticians need a way to add up coal, gas, hydro and oil in one column, and the tonne of oil equivalent does that by expressing everything as the heat from burning a tonne of crude oil. Because crude oils differ in calorific value, the figure is a convention rather than a measurement, and more than one version circulates. The International Energy Agency uses 41.868 gigajoules, which is the figure used here. Other sources use 41.85 gigajoules, and a version based on the thermochemical calorie gives 44.769.

In everyday terms the IEA value is 11,630 kilowatt-hours, or about 39.7 million British thermal units, and it equals 10 gigacalories on the international steam table calorie. Smaller and larger steps are the kilogram of oil equivalent (one thousandth) and the megatoe and gigatoe. One toe is about 7.33 barrels of oil equivalent and 1.42857 tonnes of coal equivalent. Converting electricity into toe depends on an assumed plant efficiency, so national tables can differ.

1 tonne of oil equivalent = 41,868,000,000 joules (exactly).

Sources: Wikipedia: Tonne of oil equivalent; Wikipedia: Calorie

Related conversions

See all energy units.