British thermal unit
| British thermal unit | |
|---|---|
Graph of total energy consumption in the US (divided into energy sources) in quadrillion Btu | |
| General information | |
| Unit system | imperial/US units |
| Unit of | Energy (heat) |
| Symbol | Btu |
| Conversions | |
| 1 Btu in ... | ... is equal to ... |
| SI units | ≈ 1055 J |
The British thermal unit (Btu) is a measure of heat, which is a form of energy. It was originally defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is also part of the United States customary units. The SI unit for energy is the joule (J); one Btu equals about 1,055 J (varying within the range of 1,054–1,060 J depending on the specific definition of Btu; see below).
While units of heat are often supplanted by energy units in scientific work, they are still used in some fields. For example, in the United States the price of natural gas is quoted in dollars per the amount of natural gas that would give 1 million Btu (1 "MMBtu") of heat energy if burned.