Interactive Tool: When Are You Most Fertile?

What does this tool measure?

Click here to find out when you are most likely to get pregnant .

This interactive tool estimates your peak fertility period, also known as your "fertile window." This is when you are most likely to become pregnant.

To find your peak fertility period, the tool calculates the day you are most likely to ovulate by using the date of your last menstrual period and the typical length of your menstrual cycle.

A woman is usually able to get pregnant for about 5 days each month, when ovulation occurs. On average, ovulation occurs 12 to 16 days before the menstrual period begins. The key to becoming pregnant is determining when ovulation will occur. Because sperm can live for 3 to 5 days in a woman's reproductive tract, it is possible to become pregnant if intercourse occurs several days before ovulation. This tool should not be used to prevent pregnancy.

Your menstrual cycle begins with the first day your period starts and ends the day before your next period starts. If you do not know the number of days in your menstrual cycle, use 28 days, which is the average length of a menstrual cycle. If you want to determine the length of your cycle, use a calendar to track it. Some women have longer or shorter cycles.

While women usually ovulate at day 15, it's also normal to ovulate well before or after the 15-day mark. This calculator is therefore meant to give you a rough estimate.

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Author:	Kathe Gallagher, MSW	Last Updated: February 23, 2007
Medical Review:	Adam Husney, MD - Family Medicine Tom Bailey, MD - Family Medicine
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