British Thermal Units to Gigajoules (BTU to GJ)
1 British thermal unit equals 0.000001055055853 gigajoules (rounded).
How to convert British thermal units to gigajoules
To convert British thermal units to gigajoules, multiply the number of British thermal units by 0.000001055055853. The factor is rounded to 10 significant digits. To go the other way, multiply gigajoules by 947,817.1203 (rounded).
gigajoules = British thermal units × 0.000001055055853
Example: 10 British thermal units = 0.00001055055853 gigajoules.
The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.
About these units
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
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
Related conversions
- Gigajoules to British thermal units (reverse)
- British thermal units to joules
- British thermal units to kilojoules
- British thermal units to watt-hours
- British thermal units to kilowatt-hours
- British thermal units to calories
- British thermal units to kilocalories
- British thermal units to megajoules
- British thermal units to megawatt-hours
- British thermal units to foot-pounds
- British thermal units to millijoules
- British thermal units to electronvolts
- British thermal units to kiloelectronvolts
- Joules to gigajoules
- Kilojoules to gigajoules
- Watt-hours to gigajoules
- Kilowatt-hours to gigajoules
- Calories to gigajoules
- Kilocalories to gigajoules
- Megajoules to gigajoules
- Megawatt-hours to gigajoules
- Foot-pounds to gigajoules
See all energy units.