Hey Girls, I just came across this very informative website and I thought I would share this with you. They said that the most effective way to calculate when you are most fertile is to subtract 16 from the number of days in your cycle then add 4. For instance my cycles are 26 days. So I subtract 16 from 26 leaving 10 then I add 4 making it 14. So my most fertile days would be day 10 through day 14. Anyways, I have never heard it described quit like that before. We bd on the 13th and 14th day. Still waiting. They also had alot of very descriptive stuff about your cm at all stages of you cycle and what to look for....Alot of good information! Ok , just thought I would share that with you all. GOOD LUCK!!