I don't find it to be worth my time. Fertility Friend is for the percentage of women who's cycles are the exact same every single month. If your cycles vary in days it's not going to be helpful. I'd rather write down my cycle days in my datebook and count backward 14 days to find out my ovulation dates and go from there. If your cycles are the exact same every month then I'd say try it, but if not then don't waste your money.