British thermal unit
noun
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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
Business Columnist, Los Angeles Times, 5 Mar. 2026
Goldman Sachs analysts said that a monthlong pause in LNG transit supply through the strain could send European prices and spot Asia LNG to surge 130% to $25 per million British thermal units.
—Maydeen Merino, The Washington Examiner, 4 Mar. 2026
Spot prices reached $25.40 per million British thermal unit in Asia, according to traders, more than double last week.
—Sing Yee Ong, Bloomberg, 4 Mar. 2026
Natural gas futures settled at nearly $7 per MMBtu (British thermal unit) on Jan. 27, the highest level since December 2022.
—Mary Cunningham, CBS News, 4 Feb. 2026
Meanwhile, natural gas prices surged again this morning on the bitter cold, topping $6 per million British thermal units for the first time since late 2022.
—Jim Cramer, CNBC, 26 Jan. 2026
Prices spiked more than 60% in just a few days, jumping from around $3 per million British thermal units to above $5, as expectations of surging heating demand collided with fears of supply disruptions.
—Benzinga, Freep.com, 24 Jan. 2026
That refers to a 1993 House vote on a controversial energy tax during the first year of Bill Clinton's presidency based on British thermal units.
—Bart Jansen, USA Today, 8 June 2025
Cite this Entry
“British thermal unit.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/British%20thermal%20unit. Accessed 24 Mar. 2026.
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