Not for "irregular" periods

It seemed really good and organized at first but then I realized it cannot account for periods that last longer than 5 days. When I tried to mark the 10th day of my period it said it was “too close to my previous period” but it was actually part of the same cycle. It also counts the spotting at the begining when my doc clearly stated that the first day of the cycle was the first day of real flow, not spotting the few days before. After I realized it was tracking right, I knew all the fertile days were most likely off too.

Rene Munday about Ovulation Calendar