# Units and calculators explained

Energy conversion calculators

## Calculators for energy used in the United States

Note: Btu is British thermal units.

### Coal conversion calculator

1 short ton = 18,820,000 Btu (based on U.S. electric power sector consumption in 2022; preliminary)

### Electricity conversion calculator

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

### Natural gas conversion calculator

1 cubic foot = 1,036 Btu (based on U.S. average for natural gas delivered to consumers in 2022, preliminary)

### Crude oil conversion calculator

1 barrel = 42 U.S. gallons = 5,684,000 Btu (based on U.S. production in 2022, 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 that 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
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
joule 1.0 joule
megajoule 1.0E+06 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

Last updated: June 16 2023, with preliminary data for 2022.