Distillate to water calculator help?

[LuckyAddaam]

http://www.hillbillystills.com/distilling-calculators" onclick="window.open(this.href);return false;" rel="nofollow distillate to water calculator. I'm not sure how to use this.... I'm not sure at what % my still collects. What does that even mean lol. I read it as how effecient is my still. Does it mean.... at what % it is collected @? Cause that would be silly since it changes from the beginning to the end of the run.....