The Energy in Natural Gas is 1,027 BTUs per cubic foot, which is equal to approximately 137.3 BTUs / gallon.
BTUs and Common Energy Sources
BTU stands for British Thermal Unit, and it is the amount of energy needed to heat one pound of water by one degree Fahrenheit.
Many common energy sources are used to generate energy measured in BTUs. The following is an excerpt from a U.S. Department of Energy guide listing the BTUs generated by energy products: