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What Is Energy?

Energy Calculators

From gallons to British thermal units (Btu), kilowatthours to megajoules, short tons to metric tons, this calculator converts from one energy unit to another. Btu content is based on data from the Monthly Energy Review, Appendices, August 2023.

Calculators for energy used in the United States

Note: Btu is British thermal units.

Coal conversion calculator

1 short ton = 18,934,000 Btu (based on U.S. electric power sector consumption in 2022)

Electricity conversion calculator

1 kilowatthour = 3,412 Btu (standard conversion factor)

Natural gas conversion calculator

1 cubic foot = 1,037 Btu (based on U.S. average of natural gas for end-use sectors in 2021, preliminary)

Crude oil conversion calculator

1 barrel = 42 U.S. gallons = 5,691,000 Btu (based on U.S. production in 2020, preliminary)

Gasoline conversion calculator

1 gallon = 120,238 Btu (based on U.S. finished motor gasoline [includes fuel ethanol content] consumption at 5.05 million Btu per barrel in 2021; preliminary)

Diesel fuel and heating oil conversion calculator

1 gallon = 137,381 Btu (for distillate fuel with 15 ppm or less sulfur content at 5.77 million Btu per barrel in 2021; preliminary)

Measuring energy in food

Food calories are a measure of energy in food. One food calorie is equal to 1,000 calories, or 1 kilocalorie. For example, the energy in a 300-food calorie ice cream cone is about the same as the amount of electricity required to light a 100-watt incandescent light bulb for 3.5 hours.

Food energy conversion calculator

1 food calorie = 1,000 calories, or 1 kilocalorie, or 3.9683 Btu

Scientific notation explained

Scientific notation is a short-hand way of writing a number that has a lot of digits. For example, the number 525,000,000 could be written as 5.25E+08. The +08 indicates the decimal should be moved eight places to the right. A negative number after the E means the decimal should be moved a certain number of places to the left. For example, 5.25E-03 is the same as 0.00525.

Common energy units Scientific notation
British thermal unit (Btu) 1.0
millions of Btu 1.0E+06 Btu
therm 1.0E+05 Btu
billions of Btu 1.0E+09 Btu
quad 1.0E+15 Btu
calorie 1.0 calorie
kilocalorie 1.0E+03 calories
food calorie 1.0E+03 calories
thermie 1.0E+05 calories
teracalorie 1.0E+12 calories
megajoule 1.0E+06 joule
joule 1.0 joule
gigajoule 1.0E+09 joule
terajoule 1.0E+12 joule
Watthour 1.0
kilowatthour (kWh) 1.0E+03 Watthour
megawatthour (mWh) 1.0E+06 Watthour
gigawatthour (gWh) 1.0E+09 Watthour
terawatthour (tWh) 1.0E+12 Watthour