Kilowatt-hours to British Thermal Units (kWh to BTU)

1 kilowatt-hour equals 3,412.141633 British thermal units (rounded).

1 kilowatt-hour = 3,412.141633 British thermal units

How to convert kilowatt-hours to British thermal units

To convert kilowatt-hours to British thermal units, multiply the number of kilowatt-hours by 3,412.141633. The factor is rounded to 10 significant digits. To go the other way, multiply British thermal units by 0.0002930710702 (rounded).

British thermal units = kilowatt-hours × 3,412.141633

Example: 10 kilowatt-hours = 34,121.41633 British thermal units.

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

About these units

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

British Thermal Unit (BTU)

US & ImperialCurrent unit

The International Table BTU, exactly 1,055.05585262 joules. The energy to heat one pound of water by one degree Fahrenheit; used for heating, cooling and gas appliances in the US.

Few energy units come in as many versions as the British thermal unit. It was defined as the heat needed to raise one pound of liquid water by one degree Fahrenheit, but because water's heat capacity shifts slightly with temperature, definitions differ by up to 0.5 percent: about 1,054.35 J for the thermochemical Btu, 1,054.80 J at 59 degrees Fahrenheit (used for American natural gas pricing), 1,054.68 J at 60 degrees (mainly Canadian), and 1,059.67 J at 39 degrees. A 1942 note suggests the term apparently arose in the United States and was later adopted in Britain.

The version on this site is the International Table Btu, about 1,055.06 J, which comes from the international steam table conferences that tied heat units to the joule. Joule's own 1850 experiments gave 772.692 foot-pounds of work per Btu, the number that first linked heat to mechanical effort.

Today the Btu survives in natural gas pricing (MMBtu means a million Btu), US building energy reporting, and equipment ratings in Btu per hour. One ton of air-conditioning is 12,000 Btu/h, or 3.52 kW. A single wooden kitchen match burning releases about one Btu.

1 British thermal unit = 1,055.055853 joules (approximately).

Sources: Wikipedia: British thermal unit; Wikipedia: James Prescott Joule

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