The objective of this program is to calculate a variety of properties of natural gas from a minimum of inputs. The calculated properties include the compressibility factor, specific heat at a constant pressure, ratio of specific heats, thermal conductivity, density, viscosity, saturation water content, and lower (also called ‘net’) and gross heating values. The program will calculate an approximate composition of the gas based on the temperature, pressure, specific gravity, and the nitrogen, hydrogen sulfide, carbon dioxide content of the gas. It should be noted that this program is not intended to calculate properties for hydrocarbon liquids, and error warnings will be displayed if the presence of liquids at the inputted conditions is expected.