A woman is able to become pregnant (fertile) only during a certain part of her monthly cycle. That is just before and during ovulation. By learning when you ovulate, you can predict when you’re likely to be fertile. This calculator gives approximate ovulation dates and fertile times for women who have regular periods. (Regular periods mean having a period every 21 to 35 days.) Fertility charting, basal temperature tracking, and purchased ovulation test kits can also be used to help predict a woman’s fertile times. These are especially useful if a woman has irregular periods.
Please note that the date you enter in the calculator may result in an ovulation date that has already passed. This will occur if you are nearing your next menstrual start date.
This calculator is not meant for women who are already pregnant. It cannot and should not be used as an aid to preventing pregnancy. This calculator is provided for educational purposes only. It is not intended as a substitute for professional health care. Always consult with a healthcare provider for advice concerning your health.
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Given the information you provided, your next ovulation date is estimated to be .
You are likely to be most fertile on the day of ovulation and during the 4 or 5 days just before ovulation. Studies have shown that to increase your chances of getting pregnant, you should have sex once a day or every 2 days during your fertile days. Sperm can live for a few days and the egg can live about a day. Most experts suggest you try every other day or every day starting about 5 or 6 days before you expect to ovulate. Continue up through the day of ovulation or the next day.
How is my estimated date of ovulation calculated?
On average, a woman with a regular 28-day cycle ovulates on about the 14th day of each cycle. If a woman’s cycle is longer or shorter than 28 days, the predicted ovulation date is changed accordingly. For example, during a 24-day cycle (4 days shorter than the average), ovulation takes place on about the 10th day. Similarly, changes are made in the opposite direction for cycles longer than 28 days. Stress, illness, and other things can also affect the timing of ovulation. Irregular cycles or cycles that are shorter than 21 days or longer than 35 make calendar prediction of ovulation unreliable.
This calculator is not intended to replace the evaluation of a healthcare professional.
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Author: Lambert, J.G. M.D.
© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
