Here you can use a Javascript program to calculate the height of the atmosphere assuming that the temperature and pressure do not change with height. Set the parameters as you want them and press Compute . To get back to the original values press Reset . Height Step Actual Iterations Max.
Full Results Try the effect of changing the values of the height step.
You may need to change the number of iterations as well. To check that the calculation has found the top of the atmosphere check that the Convergence flag has changed from NO to YES . If not then you may need to increase your maximum number of iterations.