Gigajoules to British Thermal Units (GJ to BTU)
1 gigajoule equals 947,817.1203 British thermal units (rounded).
How to convert gigajoules to British thermal units
To convert gigajoules to British thermal units, multiply the number of gigajoules by 947,817.1203. The factor is rounded to 10 significant digits. To go the other way, multiply British thermal units by 0.000001055055853 (rounded).
British thermal units = gigajoules × 947,817.1203
Example: 10 gigajoules = 9,478,171.203 British thermal units.
The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.
About these units
Gigajoule (GJ)
One billion joules, roughly the energy in 29 liters of petrol. Used for natural gas and district heating.
One gigajoule is a billion joules, a size that only shows up when something large is being counted. An average lightning bolt carries about that much, and the superconducting magnet of the ATLAS experiment at CERN stores about 1.1 GJ of magnetic energy.
Everyday life can reach it too, just slowly. Filling a car with about 61 liters of gasoline, roughly 16 US gallons, puts in about 2 GJ of combustion energy. A standard refrigerator uses about 4.5 GJ in a year, and an average human heart muscle expends about 3.3 GJ over an 80-year lifetime.
Larger reference points sit nearby. One megawatt-hour is 3.6 GJ, exploding a ton of TNT releases about 4.2 GJ, and a barrel of oil equivalent is about 6.1 GJ. These comparisons explain why gigajoules suit annual household or building energy tallies better than joules or kilojoules.
1 gigajoule = 1,000,000,000 joules (exactly).
Sources: Wikipedia: Orders of magnitude (energy); Wikipedia: Joule
British Thermal Unit (BTU)
The International Table BTU, exactly 1,055.05585262 joules. The energy to heat one pound of water by one degree Fahrenheit; used for heating, cooling and gas appliances in the US.
Few energy units come in as many versions as the British thermal unit. It was defined as the heat needed to raise one pound of liquid water by one degree Fahrenheit, but because water's heat capacity shifts slightly with temperature, definitions differ by up to 0.5 percent: about 1,054.35 J for the thermochemical Btu, 1,054.80 J at 59 degrees Fahrenheit (used for American natural gas pricing), 1,054.68 J at 60 degrees (mainly Canadian), and 1,059.67 J at 39 degrees. A 1942 note suggests the term apparently arose in the United States and was later adopted in Britain.
The version on this site is the International Table Btu, about 1,055.06 J, which comes from the international steam table conferences that tied heat units to the joule. Joule's own 1850 experiments gave 772.692 foot-pounds of work per Btu, the number that first linked heat to mechanical effort.
Today the Btu survives in natural gas pricing (MMBtu means a million Btu), US building energy reporting, and equipment ratings in Btu per hour. One ton of air-conditioning is 12,000 Btu/h, or 3.52 kW. A single wooden kitchen match burning releases about one Btu.
1 British thermal unit = 1,055.055853 joules (approximately).
Sources: Wikipedia: British thermal unit; Wikipedia: James Prescott Joule
Related conversions
- British thermal units to gigajoules (reverse)
- Gigajoules to joules
- Gigajoules to kilojoules
- Gigajoules to watt-hours
- Gigajoules to kilowatt-hours
- Gigajoules to calories
- Gigajoules to kilocalories
- Gigajoules to megajoules
- Gigajoules to megawatt-hours
- Gigajoules to foot-pounds
- Joules to British thermal units
- Kilojoules to British thermal units
- Watt-hours to British thermal units
- Kilowatt-hours to British thermal units
- Calories to British thermal units
- Kilocalories to British thermal units
- Megajoules to British thermal units
- Megawatt-hours to British thermal units
- Foot-pounds to British thermal units
- Millijoules to British thermal units
- Electronvolts to British thermal units
- Kiloelectronvolts to British thermal units
See all energy units.