Ovulation Calculator

On this page we explain the Ogino method used in the ovulation date calculator on this site.

The Ogino method is a famous academic theory proposed by Kyusaku Ogino in 1924. In his theory Ogino states, "Regardless of the length of the cycle, ovulation occurs in the five day period 12-16 days prior to the following menstruation."

Calculation of ovulation dates in the Ogino method is based on the theory that the ovulation date will occur in the five days (plus or minus two) fourteen days before the scheduled date of the next menstruation - the ovulation period is between 12 and 16 days before the scheduled date of the next menstruation.

The period when you are most likely to get pregnant is the fertilization period, the ovulation period plus the three days the sperm are alive and the one day the egg is alive.
The period when you are most likely to get pregnant works out to be the 9 days or the 11th to 19th days counting from the day before the next predicted date of your period.

The results may be inaccurate due to irregularities in menstruation or fluctuations in the menstrual cycle.
In order to predicate the ovulation day more accurately, you may wish to consider using this in conjunction with other methods such as basal body temperature.