We measure and sell Natural Gas in cubic feet (volume) or in British Thermal Units (heat content).  Heat from all energy sources can be measured and converted back and forth between British thermal units (Btu) and metric units.

One Btu is the heat required to raise the temperature of one pound of water one degree Fahrenheit.  Ten burning kitchen matches release 10 Btu. One cubic foot of natural gas has about 1031 Btu. A box 10 feet deep, 10 feet long, and 10 feet wide would hold one thousand cubic feet of natural gas.

For example, a candy bar has about 1000 Btu.

Pipeline companies buy natural gas in thousands of cubic feet or Mcf. M = one thousand.