But, the results are close to averages of balloon and airplane measurements at various altitudes. The table below uses metric units, which scientists use. Click here for a version using feet, fahrenheit temperatures and pressures in inches of mercury. This table give density in slugs per cubic foot because it uses the American system of altitude in feet, pressure in inches of mercury and temperature in degrees Fahrenheit. While people often use pounds per cubic foot as a measure of density in the U.S., pounds are really a measure of force, not mass.
Slugs are the correct measure of mass.
You can multiply slugs by 32.2 for a rough value in pounds. Altitude Pressure Temp. For a more detailed table or a table in metric units, consult an aerodynamics textbook. Many weather textbooks also have tables of the standard atmosphere.