A booster moves gas from a donor cylinder into a receiving cylinder and keeps going past the point where the two would level off on their own. The calculator shows the end pressures, the new mix in the receiving cylinder and how much gas moved, with the real properties of oxygen, helium and nitrogen.
It also estimates how long the job takes at your booster’s flow, how hot the gas gets when it is compressed without cooling, and roughly how much drive air an air-driven booster uses, so you know before you start whether your drive air will last.