This application calculates the rate at which gas flows out of a hole (or throat) in a pressurized pipe. Additionally, the Mach number, gas temperature and velocity, and speed of sound at the throat are computed. The same analysis can be applied to a pressurized tank venting gas through a hole, as long as the internal conditions are constant. The hole is small compared to the pipe diameter (so that the gas vents at a greater rate than the bulk flow of gas through the pipe), and the process is at steady-state and isentropic.