British Thermal Unit and Other Conversion Factors
British Thermal Unit (Btu) Conversion Factors
The thermal conversion factors in the following tables can be used to estimate the heat content in British thermal units (Btu) of a given amount of energy measured in physical units, such as barrels or cubic feet. For example, 10 barrels of asphalt has a heat content of approximately 66.36 million Btu (10 barrels x 6.636 million Btu per barrel = 66.36 million Btu). The heat content rates (i.e., thermal conversion factors) represent the gross (or higher or upper) energy content of the fuels. We apply gross heat content rates in all Btu calculations for the Monthly Energy Review, and they are commonly used in energy calculations in the United States; net (or lower) heat content rates are typically used in European energy calculations. The difference between the net and gross heat content rates is the amount of energy needed to vaporize the water created during the combustion process. Generally, the difference ranges from 2% to 10%, depending on the fuel and that fuel’s hydrogen content. Some fuels, such as unseasoned wood, can be more than 40% different in their gross and net heat content rates. “Heat content” and “British Thermal Unit (Btu)” in the Glossary provides additional information.
Other Conversion Factors
Data presented in U.S. Energy Information Administration publications are expressed predominately in units that historically have been used in the United States, such as British thermal units, barrels, cubic feet, and short tons. The metric conversion factors can be used to calculate the metric-unit equivalents of values expressed in U.S. customary units. For example, 500 short tons are the equivalent of 453.6 metric tons (500 short tons x 0.9071847 metric tons/short ton = 453.6 metric tons). The other conversion factors can be used to calculate equivalents in various physical units commonly used in energy analyses. For example, 10 barrels are the equivalent of 420 U.S. gallons (10 barrels x 42 gallons/barrel = 420 gallons).
Source: U.S. Energy Information Administration, Conversion Factors - Notes and Sources