The application calculates the oxygen content in the air, taking into account humidity and temperature. It can be useful when calibrating by "air" oxygen measuring devices, to take into account the decrease in the volume fraction of oxygen. by replacing oxygen with water vapor. Also calculated the dew point, and the absolute humidity of the air. The calculation is available for the following conditions: - temperatures from -60 to + 83 degrees Celsius, - atmospheric pressure from 600 to 860 mm Hg, - relative humidity from 0 to 100%