Pool estimates, especially for coins with bonus blocks, are generally not accurate in my experience.
There are to many short term variables for the estimates to be correct. I'd do the math myself.
For those of you that do not know; Almost all pools are a copy/paste of the first LTC pool. This is the source;
https://github.com/MPOS/php-mposIt was coded by TheSerapher. This info can be found by scrolling to the bottom of the page on any pool. Don't expect estimates to be correct.