Electronvolts to Kilowatt-hours (eV to kWh)

1 electronvolt equals 4.45049065×10⁻²⁶ kilowatt-hours exactly.

1 electronvolt = 4.45049065×10⁻²⁶ kilowatt-hours

How to convert electronvolts to kilowatt-hours

To convert electronvolts to kilowatt-hours, multiply the number of electronvolts by 4.45049065×10⁻²⁶. This factor is exact. To go the other way, multiply kilowatt-hours by 2.246943267×10²⁵ (rounded).

kilowatt-hours = electronvolts × 4.45049065×10⁻²⁶

Example: 10 electronvolts = 4.45049065×10⁻²⁵ kilowatt-hours.

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

About these units

Electronvolt (eV)

ScientificCurrent unit

Exactly 1.602176634×10⁻¹⁹ joules, the energy gained by an electron moving through one volt. Used in atomic and particle physics.

Particle physicists adopted this unit because a charged particle crossing a voltage V gains energy qV, so an electron accelerated through one volt in a vacuum gains exactly one electronvolt. Since the 2019 revision of the SI, the elementary charge is fixed, which makes 1 eV exactly 1.602176634 x 10^-19 J. The NIST appendix page still shows a rounded, non-exact value, reflecting the time before this redefinition. The unit is not part of the SI itself.

It suits the atomic world. Visible photons carry roughly 1.65 to 3.26 eV, green light at 532 nm is about 2.33 eV, and ionising hydrogen needs 13.6 eV. Molecular bonds are on the order of 1 to 10 eV each, and thermal motion at 20 degrees Celsius corresponds to about 0.025 eV. Particle masses are also quoted in eV/c squared, so the proton is about 938 million of them. Larger multiples such as keV, MeV and GeV extend the scale upward.

1 electronvolt = 1.602176634×10⁻¹⁹ joules (exactly).

Sources: Wikipedia: Electronvolt; NIST SP 811, Appendix B.8 (energy conversion factors)

Kilowatt-hour (kWh)

Metric (SI)Current unit

3.6 million joules, the energy used by a 1,000-watt appliance in an hour. The billing unit for household electricity.

Before it was a line on every power bill, the kilowatt-hour had a British nickname: the Board of Trade unit, abbreviated B.T.U. after the government body that regulated the electricity industry until 1942, when the Ministry of Power took over. In India it is still often called simply a unit, and a million of them, written MU, is a gigawatt-hour.

A kilowatt-hour is the energy of a 1 kW device running for an hour, which is 3.6 MJ, or about 3,412 British thermal units. A 100 W television watched for 10 hours uses one, and boiling a liter of water in an electric kettle takes about 0.1. In 2020 the average US household used 893 kWh a month, an average continuous draw of about 1.22 kW.

Utilities multiply the kilowatt-hours consumed by a price per kWh, and larger customers may also pay for peak demand. One common error is writing kW/h, which would mean kilowatts per hour, a rate of change of power, not energy.

1 kilowatt-hour = 3,600,000 joules (exactly).

Sources: Wikipedia: Kilowatt-hour; Wikipedia: British thermal unit; Wikipedia: Watt-hour

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