Horsepower-hours to Kilowatt-hours (hp⋅h to kWh)

1 horsepower-hour equals 0.7456998716 kilowatt-hours (rounded).

1 horsepower-hour = 0.7456998716 kilowatt-hours

How to convert horsepower-hours to kilowatt-hours

To convert horsepower-hours to kilowatt-hours, multiply the number of horsepower-hours by 0.7456998716. The factor is rounded to 10 significant digits. To go the other way, multiply kilowatt-hours by 1.34102209 (rounded).

kilowatt-hours = horsepower-hours × 0.7456998716

Example: 10 horsepower-hours = 7.456998716 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

Horsepower-hour (hp⋅h)

US & ImperialTraditional unit (still used in some regions)

About 2.685 MJ (0.7457 kWh), the energy of one mechanical horsepower for an hour.

Multiplying a power by a time gives energy, and this unit does it with James Watt's horse. In the late 18th century Watt compared steam engines with the draft horses they replaced. After an experiment in 1782 that suggested a brewery horse delivered 32,400 foot-pounds per minute, he and Matthew Boulton rounded the figure to 33,000 foot-pounds per minute the next year. One mechanical horsepower is therefore about 745.7 W, and sustaining it for an hour gives roughly 2.685 MJ, or 0.7457 kWh.

The unit is now outdated and outside the SI. Railways still use it to settle accounts when locomotives are lent between companies. In one example, a 2,500 hp unit used for 12 hours is owed back as 30,000 hp-hours, repayable with a 3,000 hp unit for 10. A German variant, the Pferdestaerkenstunde, uses the metric horsepower of about 735.5 W and equals 2,647.7955 kJ, so one hp-hour is about 1.014 PSh.

1 horsepower-hour = 2,684,519.538 joules (approximately).

Sources: Wikipedia: Horsepower-hour; Wikipedia: Horsepower; Wikipedia: Conversion of units of energy

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

Related conversions

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