Another update to the calculator:
this one adds another sensitivity analysis to the calculator, based on varying stock returns (for a single case and for the monte carlo simulation).
If you pick a constant stock return (e.g 8.1%), it will calculate your time to retirement using a bunch of different returns from 60% lower (i.e. 3.2%) all the way up to 60% higher (12.9%). For the monte carlo simulation, it does the same but shifting the mean of the distribution to these levels before drawing the annual returns that go into the model and then running a retirement cycle thousands of times.