In order to calculate your fertile days it is necessary to consider that the conception always happens in the middle of the cycle, that is, around the 14th day of a normal cycle of 28 days.
To find out which are your fertile days, it is necessary to count 14 days from the date of your last period. The ovulation will occur between 3 days before and 3 days after that date, which is what is considered a woman's fertile days.
Put in your data and find out when is your fertile period so you can schedule your pregnancy or protect yourself from an unwanted pregnancy.
How to calculate your fertile days with an irregular cycle
Calculating your fertile days in an irregular cycle is not reliable for those who are trying to get pregnant or for those who do not want to get pregnant, because the menstrual cycle does not always come at the same period, the math may be wrong.
However, one way of knowing when is the most fertile days in irregular cycles is to note the duration of each menstrual cycle for one year and then subtract 18 days to the shortest cycle and 11 days to the longest cycle.
For example: If your shortest cycle was 22 days and the longest cycle 28 days, then: 22 - 18 = 4 and 28 - 11 = 17, so your fertile days will be between the 4th and the 17th days of the cycle.
A more rigorous way of knowing your fertile days in an irregular cycle for women who wish to become pregnant is use ovulation tests that are bought at pharmacies and be vigilant for signs of your fertile days, such as egg white discharge. For those who do not wish to get pregnant, the calendar-based method is not an effective one and, therefore, it is important to use safe contraceptive methods, such as a condom or a contraceptive pill, for example.