A cubic foot, or cf, is the most common unit of measurement of gas volume. One cf of natural gas is the amount of gas required to fill a volume of one cubic foot under stated conditions of temperature, pressure, and water vapor. Natural gas is often measured in larger quantities as well, such as Mcf (1,000 cf), MMcf (1 million cf) and Bcf (1 billion cf). The energy content of a cubic foot of natural gas varies depending on the heating value of the specific quantity of gas. A typical value in the United States is 1,015 MMBtu per 1 MMcf.
Cubic foot conversion table
| 1,000 cf = | 1 Mcf |
| 1,000,000 cf = | 1 MMcf |
| 1,000,000,000 cf = | 1 Bcf |
| 1 MMcf = | 1,105 MMBtu* |
* This conversion varies with the energy content of gas