Fertile Period Calculator (and how to calculate it)

The fertile period calculator is a simple and quick way to identify the most fertile days, simply filling in the date of the last menstruation and how many days the menstrual cycle normally has.

To find out when your next fertile period will be, fill in the calculator with the data from your last period:

O result of this calculator works only for women who have a regular cycle. In cases of an irregular cycle, another formula must be used. See how to calculate the fertile period in an irregular cycle.

Identifying the days of the fertile period is important for women who are trying to get pregnant, as it increases the chances of pregnancy. However, calculating the fertile period should not be used as a natural contraceptive method, as it may fail. Find out how to choose the best contraceptive method.

What is the fertile period

The fertile period is the time in the menstrual cycle when ovulation occurs and the woman has a greater chance of becoming pregnant. This period lasts approximately 6 days and occurs 10 to 14 days after the first day of menstruation.

Read too: Fertile Period: when it is, symptoms (and how to calculate)

How to calculate the fertile period

To calculate the fertile period, a woman must count 14 days after the first day of her last menstrual period and then add 3 days before and 3 days after, to identify the interval of the 7 most fertile days. This calculation works best for women who have a regular 28-day cycle.

In the case of smaller regular cycles, such as 24 or 26 days, for example, the woman should find the day that marks the middle of this period, as it is around that day that ovulation occurs. Thus, in the case of the 24-day cycle, ovulation occurs close to the 12th day, instead of the 14th.

Make an appointment with your nearest gynecologist, using the following tool, to better understand how the menstrual cycle works and how to calculate your fertile period:

Calculate fertile period in an irregular cycle

In the case of women with an irregular menstrual cycle, the fertile period is more difficult to calculate, as the middle of each (irregular) cycle cannot be identified.

However, there are some ways to try to predict, with less precision, the fertile period in cases of irregular periods. One of the most used ways is to write down the duration of each cycle for a year and then subtract 18 days from the shortest cycle and 11 days from the longest cycle.

The period of days between results indicates the fertile period in each cycle. As it is less accurate, this method also offers a longer period of days.

For example: if the shortest cycle was 22 days and the longest cycle was 28 days, then: 22 – 18 = 4 and 28 – 11 = 17, that is, the fertile period must be considered between the 4th and 17th days of the cycle . See more details about the fertile period in the irregular cycle.

Read too: How to calculate the fertile period of the irregular cycle

How do I know if I am fertile?

The fertile period can be identified through some signs, such as:

• Increased vaginal secretion;
• Increase in body temperature;
• Increased appetite;
• Increased libido.

The signs and symptoms of the fertile period occur when the egg is released by the ovary and reaches the Fallopian tubes, ready to be fertilized by sperm and begin pregnancy. Check out a list of the most common symptoms during the fertile period.