Whole Farm > Weight & Measurements

## Energy Measurements and Conversions

### Common Prefixes and Abbreviations

Deka = ten
Hecto = hundred
Kilo = thousand
Mega = million
Giga = billion
Tera = trillion

British thermal unit (Btu)
Kilocalories (kcal)
Kilojoule (kJ)
Kilowatt (kW)
Megawatt (MW)
Gigawatt (GW)
Terawatt (TW)
Watthour (Wh)
Kilowatthour (kWh)
Megawatthour (MWh)
Gigawatthour (GWh)
Terawatthour (TWh)

1 metric ton = 2,204.62 pounds
1 metric ton = 1.1023 short tons
1 kiloliter = 6.2898 barrels (crude oil)
1 barrel = 42 gallons
1 kiloliter = 1 cubic meter

### British Thermal Unit (Btu) Measurements and Conversions

Approximate definition: A British thermal unit is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

1 Btu = 252 International Table calories
1 calorie = .00397 Btu
1 Btu = .252 kilocalories
1 kilocalorie = 3.968 Btu
1 Btu = 1,055.05585 joules
1 Btu = 1.055 kilojoules
1 kilojoule = .947817 Btu
1 therm = 100,000 Btu
1 dekatherm = 10 therms
1 dekatherm = 1 million Btu
1 kilowatthour = 3,412 Btu
1 horsepower = 2,545 Btu per hour

### Joule Measurements and Conversions

Approximate definition: the energy required to lift one newton (102 g or a small apple) one meter against Earth’s gravity.

1 joule = .0009478 Btu
1 Btu = 1,055.05585 joules
1 kilojoule = 1,000 joules
1 kilojoule = .947817 Btu
1 Btu = 1.055 kilojoules
1 kilojoule = .239 kilocalories
1 kilocalorie = 4.1868 kilojoules
1 watthour = 3,600 joules
1 kilowatthour = 3.6 megajoules
1 megajoule = 1 million joules
1 terajoule = 1 million megajoules

### Electricity Measurements and Conversions

Watt

Approximate definition: A human climbing a flight of stairs is doing work at the rate of about 200 watts.
Source: convertworld.com

1 watt = 1 joule per second
1 watt = 3.412 Btu per hour
1 Btu per hour = .293 watts
1 kilowatt = 1,000 watts
1 kilowatt = 3,412 Btu per hour
1 kilowatt = 1.341 horsepower (electric)
1 horsepower (electric) = .7457 kilowatts
1 megawatt = 1 million watts
1 gigawatt = 1 billion watts
1 terawatt = 1 trillion watts
1 gigawatt = 1 million kilowatts

Watthours

Approximate definition: One watthour is the amount of (usually electrical) energy expended by a one-watt load (e.g., light bulb) drawing power for one hour.
Source: US Department of Energy

1 watt second = 1 joule
1 watt minute = 60 joules
1 watthour = 3,600 joules
1 watthour = 3.6 kilojoules
1 kilowatthour = 3.6 megajoules
1 megajoule = .278 kilowatthours
1 kilowatthour = 3,412 Btu
1 kilowatthour = 860 kilocalories
1 kilowatthour = 3,600 kilojoules
1 kilowatthour = 1.341 horsepower hours (electric)
1 horsepower hour (electric) = .7457 kilowatthours
1 kilowatthour = 1 thousand watthours
1 megawatthour = 1 million watthours
1 gigawatthour = 1 billion watthours
1 terawatthour = 1 trillion watthours
1 gigawatthour = 1 million kilowatthours
1 terawatthour = 1 billion kilowatthours
1 terawatthour = 1 million megawatthours

### Power Measurements and Conversions

1 Btu per second = 1.055 kilowatts
1 Btu per second = 1.415 horsepower (electric)
1 Btu per second = 1.434 horsepower (metric)
1 Btu per second = .252 kilocalories per second
1 kilowatt = .9478 Btu per second
1 kilowatt = 1.341 horsepower (electric)
1 kilowatt = 1.3596 horsepower (metric)
1 kilowatt = .2388 kilocalories per second
1 horsepower (electric) = .7457 kilowatts
1 horsepower (electric) = 1.014 horsepower (metric)
1 horsepower (electric) = .1782 kilocalories per second
1 horsepower (electric) = .7068 Btu per second
1 horsepower (metric) = .9863 horsepower (electric)
1 horsepower (metric) = .7355 kilowatts
1 horsepower (metric) = .1757 kilocalories per second
1 horsepower (metric) = .6971 Btu per second

### References and Conversion Calculators

Biomass Energy Datebook, US Department of Energy

BP Conversion Factors

Energy Kids Page, EIA

Monthly Energy Review, EIA

Units and Calculators Explained, EIA

The International System of Units (SI) - Conversion Factors for General Use

Conversion Calculator for Units of Power, Oklahoma Local Technical Assistance Program (LTAP)

Note: This document includes units of measurement that may have more than one definition. Refer to sources listed for more detailed information.

Don Hofstrand, retired extension value added agriculture specialist, agdm@iastate.edu