They basically show, how much variance you should expect to see. What you need to know about them is that at any given time your winnings will be within these intervals with a probability of 70% and 95% respectively.

Thirdly the calculator displays the 70% and 95% confidence intervals as light and dark green curves.

This number will appear as a rather boring straight and black line in the graph. It’ll also calculate the expected winnings over the number of hands. The first thing the Variance Calculator does is to run 20 samples over the number of hands, win rate and standard deviation specified.