A woman can conceive during a specific part of the month just before and during ovulation. By learning when you ovulate, you can predict when you’re likely to be more fertile. This calculator provides approximate ovulation dates and generative times for women who have regular periods. Regular periods mean having the period every 21 to 40 days. If you’re having trouble remembering dates and consing up the days on your fingers, don’t worry – use our pregnancy due date calculator to work out your baby's due date. All you need to do is use their ovulation calendar and put in the first day of your last period. Then we need to know the average length of your menstrual cycle so we can calculate the time when you're most fertile. While the average period lasts 28 days, anything from 22 to 36 days is perfectly normal, so enter your number and check. How to use the pregnancy calculator to figure out the due date You might not be aware of your menstrual and ovulation