Energy Units Explained


Different types of energy are measured by different physical units:

  • Barrels or gallons for petroleum (such as gasoline, diesel fuel, and jet fuel)
  • Cubic feet for natural gas
  • Tons for coal
  • Kilowatt hours for electricity

To compare different fuels, we need to convert the measurements to the same units.

Units for comparing energy

Some popular units for comparing energy include British thermal units (Btu), barrels of oil equivalent, metric tons of oil equivalent, metric tons of coal equivalent, and terajoules.

In the United States, Btu, a measure of heat energy, is the most commonly used unit for comparing fuels. Because energy used in different countries comes from different places, Btu content of fuels varies slightly from country to country.

Btu content of each fuel provided below is the average heat content for fuels consumed in the United States in 2014.

Btu content of common energy units:

  • 1 barrel (42 gallons) of crude oil = 5,800,000 Btu (for U.S. produced crude oil)
  • 1 gallon of gasoline = 120,476 Btu
  • 1 gallon of diesel fuel = 137,381 Btu (distillate fuel with less than 15 parts per million sulfur content)
  • 1 gallon of heating oil = 138,500 Btu (distillate fuel with 15 to 500 parts per million sulfur content)
  • 1 barrel of residual fuel oil = 6,287,000 Btu
  • 1 cubic foot of natural gas = 1,028 Btu
  • 1 gallon of propane = 91,333 Btu
  • 1 short ton (2,000 pounds) of coal = 19,622,000 Btu
  • 1 kilowatt hour of electricity = 3,412 Btu


Learn More

Heat contents for fuels and electricity —

Btu heat contents for fuels and electricity by country —

Energy prices —