BTU (British thermal unit)
A traditional unit of heat, approximately the energy needed to raise one pound of water by one degree Fahrenheit; 1 BTU (IT) = 1,055.06 J.
The British thermal unit remains standard in the United States for fuel heat content, natural gas pricing, power plant heat rates, furnace and boiler ratings, and air-conditioner capacity. Several definitions exist, differing in the fourth significant figure; the International Table BTU is the most common.
1 kWh = 3,412.14 BTU
1 BTU/h = 0.29307 W; 1 W = 3.412 BTU/h
1 therm = 100,000 BTU = 105.5 MJ = 29.307 kWh
1 MMBtu = 10⁶ BTU = 1.05506 GJ = 293.07 kWh
1 quad = 10¹⁵ BTU = 1.055 EJ
1 ton of cooling = 12,000 BTU/h = 3.517 kW
Typical heat contents (EIA, higher heating value): natural gas about 1,036 BTU per cubic foot; crude oil 5.69 MMBtu per barrel (EIA) or 5.8 by the boe convention; diesel about 137,000 BTU per gallon; gasoline about 120,000 BTU per gallon (E10); propane about 91,450 BTU per gallon; bituminous coal about 19–26 MMBtu per short ton.
Air conditioners and heat pumps are often sized in BTU/h (a "12k" mini-split delivers about 3.5 kW), and cooling efficiency in the US uses BTU/Wh (SEER). Natural gas is traded per MMBtu at Henry Hub and billed to homes per therm.
Related terms
All terms →- MMBtu
One million British thermal units (1.05506 GJ, 293.07 kWh); the standard pricing unit for natural gas and LNG in the United States and Asia.
- Therm
A unit of heat equal to 100,000 BTU (105.5 MJ, 29.307 kWh), used for billing natural gas to homes and businesses in the US and formerly the UK.
- Joule (J)
The SI unit of energy, work and heat: the work done by a force of one newton over one metre, or one watt sustained for one second.
- Heat rate
The fuel energy a thermal power plant consumes per kWh of electricity generated; the inverse of efficiency, usually in BTU/kWh or kJ/kWh.
- SEER
Seasonal Energy Efficiency Ratio: total cooling output over a cooling season divided by electricity used, in BTU/Wh (US) or W/W (EU).
- Kilowatt-hour (kWh)
A unit of energy equal to one kilowatt of power sustained for one hour, or 3.6 megajoules; the standard billing unit for electricity.