This is not 100% accurate, most women ovulate between day 11 and day 21, dont forget to read my complete guide to predicting your ovulation date

The ovulation date is the date when the egg is released from the ovary.

It is important to know the approximate ovulation date, especially if you are finding it very difficult to conceive. It signifies the most fertile period of a woman’s cycle.(Ovulation occurs in the mid-cycle which is approximately day 14th in a regular 28 day cycle) If you are planning to conceive, it is the best period for you to have unprotected sex with your partner.

Some women don’t have a regular 28 day cycle, thereby making it more difficult to predict the ovulation date.