British thermal unit

noun

: the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at a specified temperature (such as 39°F)

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Despite its name, the British thermal unit, or BTU, may be more widely used in North America than in Britain. Air conditioners, furnaces, and stoves are generally rated by BTUs. (Though "BTUs" is often short for "BTUs per hour;" in air-conditioner ratings, for instance, "BTUs" really means "BTUs of cooling capacity per hour".) Fuels such as natural gas and propane are also compared using BTUs. The BTU first appeared in 1865 and isn't part of the metric system—the metric unit of energy is the much smaller joule—so it isn't much used by scientists, but its practicality keeps it popular for consumer goods and fuels. A better-known heat unit is the calorie; a BTU is equal to about 252 calories. (Since the familiar food calorie is actually a kilocalorie, a BTU equals only about a quarter of a food calorie.)

Examples of British thermal unit in a Sentence

Recent Examples on the Web

For example, the Maryland Bioenergy Center is capable of processing up to 110,000 tons of food waste annually, producing 312 billion British thermal units of renewable natural gas and more than 15,000 tons of fertilizer, the Agriculture Dive piece said. —Sergey Buchin, Forbes, 23 Oct. 2024

Futures for the Dutch Title Transfer Facility (TTF) hub, a European benchmark for natural gas transactions, were trading at $12.78 per million metric British thermal unit on Wednesday on the New York Mercantile Exchange. —Lee Ying Shan, CNBC, 23 Oct. 2024

Energy Shawn Hill, an expert pitmaster and owner of The Grilling Dad, says to also consider the BTU (British thermal units), which tells you the overall energy a patio heater uses to raise the temperature. —Jessie Quinn, People.com, 1 Oct. 2024

This Black and Decker Portable Air Conditioner packs 6,000 British thermal units of cooling power into a body that's about the size of a medium suitcase. —Clint Davis, Peoplemag, 22 July 2024

One British thermal unit is equivalent to 1,055 joules and will raise the temperature of one pound of water one degree Fahrenheit. —Matthew J. C. Clark, Harper's Magazine, 21 June 2024

On a gas grill that capacity is measured in BTUs (British thermal units), so the higher the BTUs the better the grilling experience. —Emily Farris, Bon Appétit, 28 Mar. 2024

Sources in Singapore suggest April spot cargoes are changing hands between $8 and $9.25 per million British thermal units (mmBtu). —Gaurav Sharma, Forbes, 27 Mar. 2024

Futures for February delivery have now risen for six straight trading sessions, including Tuesday's 7% jump to $3.19 per million British thermal units. —Ryan Dezember, WSJ, 9 Jan. 2024

Word History

First Known Use

1865, in the meaning defined above

Kids Definition

British thermal unit

noun

: the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at a specified temperature (as 39°F or 60°F) and equal to about 1055 joules

—called also Btu

Medical Definition

British thermal unit

noun

: the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at a specified temperature (as 39°F)

—abbreviation Btu