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Information about British Thermal Unit

“BTU” redirects here. For the Board of Trade Unit, see Watt-hour.
The British thermal unit (BTU or Btu) is a unit of energy used in the United States of America, particularly in the power, steam generation and heating and air conditioning industries. Although it is still used 'unofficially' in metric English-speaking countries (such as Canada, the United Kingdom, and sometimes in New Zealand), it is increasingly an outmoded and outdated unit of measure. Elsewhere (and always in scientific use) the BTU has been replaced by the SI unit of energy, the joule (J).

In North America, the term "BTU" is used to describe the heat value (energy content) of fuels, and also to describe the power of heating and cooling systems, such as furnaces, stoves, barbecue grills, and air conditioners. When used as a unit of power, BTU per hour (BTU/h) is understood, though this is often confusingly abbreviated to just "BTU". In the UK and other parts of the world it is written BTU.

The unit MBTU was defined as one thousand BTU presumably from the Roman numeral system where "M" stands for one thousand (1,000). There is currently a social push to redefine MBTU as one million (1,000,000) BTU, since the metric system uses "M" to mean mega, or 106. To avoid confusion many companies and engineers use MMBTU to represent one million (1,000,000) BTU.

Definitions

A BTU is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Melting a pound of ice at 32 °F requires 143 BTU. As is the case with the calorie, several different definitions of the BTU exist, which are based on different water temperatures and therefore vary by up to 0.5%:

Name or temperature Value (J) Notes
39 °F≈ 1059.67Uses the calorie value of water at its maximum density (4 °C)
Mean≈ 1055.87Uses a calorie averaged over water temperatures 0 °C to 100 °C
IT≡ 1055.05585262The most widespread BTU, uses the International [Steam] Table (IT) calorie, which was defined by the Fifth International Conference on the Properties of Steam (London, July 1956) to be exactly 4.1868 J
ISO≡ 1055.056International standard ISO 31-4 on Quantities and units – Part 4: Heat, Appendix A. This value uses the IT calorie and is rounded to a realistic accuracy|-59 °F≡ 1054.804Chiefly American. Uses the 15 °C calorie, itself defined as exactly 4.1855 J (Comité international 1950; PV, 1950, 22, 79-80)
60 °F≈ 1054.68Chiefly Canadian
63 °F≈ 1054.6
Thermochemical≡ 1054.35026444Uses the "thermochemical calorie" of exactly 4.184 J

Conversions

One BTU is approximately:
  • The energy produced by burning one wooden match
  • 1,054—1,060 joules
  • 252—253 cal (calories, small)
  • 0.252—0.253 kcal (kilocalories)
  • 778—782 ft·lbf (foot-pounds-force)
Other conversions:
  • In natural gas, by convention 1 MMBtu (1 million BTU, sometimes written "mmBTU") = 1.054615 GJ. Conversely, 1 gigajoule is equivalent to 26.8 m³ of natural gas at defined temperature and pressure. So, 1 MMBtu = 28.263682 m³ of natural gas at defined temperature and pressure.
  • 1 standard cubic foot of natural gas ≈ 1030 BTU (between 1010 BTU and 1070 BTU, depending on quality)

Associated units

The BTU per hour (BTU/h) is the unit of power most commonly associated with the BTU. The BTU should not be confused with the Board of Trade Unit (B.O.T.U.), which is a much larger quantity of energy (1 kW·h, or about 3412 BTU).

See also

External links

watt-hour (symbol W·h or Wh) is a unit of energy. It is most commonly used on household electricity meters in the form of the kilowatt-hour (kW·h or kWh), which is 1,000 watt-hours.
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energy (from the Greek ενεργός, energos, "active, working")[1] is a scalar physical quantity that is a property of objects and systems of objects which is conserved by nature.
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Si, si, or SI may refer to (all SI unless otherwise stated):

In language:
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  • sì (accented) for "yes"
  • si

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The joule (IPA: [dʒuːl] or [dʒaʊl]) (symbol: J) is the SI unit of energy.
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North America is a continent [1] in the Earth's northern hemisphere and (chiefly) western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the south and west
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energy (from the Greek ενεργός, energos, "active, working")[1] is a scalar physical quantity that is a property of objects and systems of objects which is conserved by nature.
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In physics, power (symbol: P) is the rate at which work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time.
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pound or pound-mass (abbreviations: lb, ℔, lbm, or sometimes in the United States: #) is a unit of mass (sometimes called 'weight' in everyday parlance) in a number of different systems, including English units, Imperial units, and United
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Water is a common chemical substance that is essential to all known forms of life.[1] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor.
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Fahrenheit is a temperature scale named after the German-Dutch physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724.

In this scale, the melting point of water is 32 degrees Fahrenheit (written “32 °F”), and the boiling point is
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A calorie is a unit of measurement for energy. Calorie is French and derives from the Latin calor (heat). In most fields, it has been replaced by the joule, the SI unit of energy.
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A calorie is a unit of measurement for energy. Calorie is French and derives from the Latin calor (heat). In most fields, it has been replaced by the joule, the SI unit of energy.
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London
Canary Wharf is the centre of London's modern office towers
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19th century - 20th century - 21st century
1920s  1930s  1940s  - 1950s -  1960s  1970s  1980s
1953 1954 1955 - 1956 - 1957 1958 1959

Year 1956 (MCMLVI
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International Organization for Standardization (Organisation internationale de normalisation), widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations.
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The term International Standard may refer to
  • International standard
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ISO 31-4 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to heat.

Its definitions include:

Quantity Unit Remarks
Name Symbol Name Symbol Definition
thermodynamic temperature T, (
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Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
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A calorie is a unit of measurement for energy. Calorie is French and derives from the Latin calor (heat). In most fields, it has been replaced by the joule, the SI unit of energy.
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The joule (IPA: [dʒuːl] or [dʒaʊl]) (symbol: J) is the SI unit of energy.
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A calorie is a unit of measurement for energy. Calorie is French and derives from the Latin calor (heat). In most fields, it has been replaced by the joule, the SI unit of energy.
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The foot-pound force, or simply foot-pound (symbol: ft·lbf or ft·lb) is an English unit of work or energy. It is the amount of energy expended when a force of one pound acts through a distance of 1 foot along the direction of the force.
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gas, especially when compared to other energy sources such as electricity. Before natural gas can be used as a fuel, it must undergo extensive processing to remove almost all materials other than methane.
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gas, especially when compared to other energy sources such as electricity. Before natural gas can be used as a fuel, it must undergo extensive processing to remove almost all materials other than methane.
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WATT

City of license Cadillac, Michigan
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Frequency 1240 kHz
Format News-Talk-Sports
Power 1,000 watts
Class C
Owner MacDonald Garber Broadcasting
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Horsepower (hp) is the name of several non-metric units of power. The most occurring conversion of horsepower to watt goes 1 horsepower = 745.7 watts. In scientific discourse, the term "horsepower" is seen as inferior and is rarely used because of its various definitions and
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ton:
  1. long ton (simply ton in countries such as the United Kingdom which formerly used the Imperial system of weights and measures) is a weight ton or gross ton, and is 2,240 lb (exactly 1,016.0469088 kg).

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The short ton (S/T) is a unit of mass equal to 2,000 lb (exactly 907.18474 kg). In the United States it is often called simply ton without distinguishing it from the metric ton (or tonne
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