Natural Gas is usually measured by volume and is stated in cubic feet. A cubic foot of gas is the amount of gas needed to fill a volume of one cubic foot under set conditions of pressure and temperature.To measure larger amounts of natural gas, a "therm" is used to denote 100 cubic feet, and "mcf" is used to denote 1,000 cubic feet.

To provide greater accuracy in comparing fuels, energy content is measured in terms of "British Thermal Units (BTU's)." A BTU is the amount of heat required to raise one pound of water (approximately a pint), one degree Farenheit at or close to its point of maximum density.

The energy content of natural gas differs in various locations thoughout the country.  For the sake of comparison, one average cubic foot of natural gas about 1,000 BTU's of heat energy.The chart below shows how much heat energy is released in various quantities of natural gas.

UNIT OF MEASURE	APPROX. HEAT ENERGY
1 cubic foot	1,000 BTU's
100 cubic feet (1 therm)	100,000 BTU's
1,000 cubic feet (1 mcf)	1,000,000 BTU's