How to Figure Out Your Ovulation Date

The most fertile time during the menstrual cycle is ovulation, which happens when the ovaries release a mature egg that travels through the fallopian tubes. The egg stays in the reproductive tract for about 12-24 hours, and if it becomes fertilized with sperm during that time, a person can become pregnant.

For people looking to conceive, it's advised to time sexual intercourse or complete fertility treatments (such as IUI) during ovulation. But how exactly does someone calculate ovulation? As it turns out, there are several methods, including using an ovulation predictor kit, monitoring your cervical mucus, charting your basal body temperature, and more.

We turned to the experts to learn more about figuring out when you're most fertile to maximize your success while trying to get pregnant.

Determining Your Fertile Window

After the egg is released, it survives for about 12-24 hours in the reproductive tract. However, sperm can live from three to five days, according to Staci Pollack, MD, an OB-GYN for the Division of Reproductive Endocrinology & Infertility at Montefiore Health System. Therefore a person can conceive during the five days before ovulation, the day of ovulation, and the day after, otherwise known as the fertile window.

It's important to remember that you can also get pregnant outside your fertile window in some instances. Factors such as having irregular periods, your ovulation timing changing month-to-month, and the sperm's ability to live for up to five days can spell a positive on that pregnancy test.

When Is My Ovulation Date?

Most people of child-bearing age ovulate about halfway through their menstrual cycle, according to Sharifa Menon, MD, FACOG, an OB-GYN at Westchester Medical Center, the flagship of the Westchester Medical Center Health Network (WMCHealth). The average cycle is 28 days, but there's a wide variation of normal, which can skew these results.

For a rough estimate of your ovulation date, subtract 14 days from the date you expect your next period to begin. Here are some ovulation date examples, considering that "day one" is the first day of your menstrual period:

• If your cycle is 28 days, you'll probably ovulate on day 14.
• If your cycle is 30 days, you'll probably ovulate on day 16.
• If cycle is 21 days, you’ll probably ovulate around day 7.

However, the ovulation date depends on the length and regularity of your menstrual cycle—and it can be harder to tell when you're ovulating if your cycle varies from month to month.

Ovulation Date Calculator Methods

Although every person who menstruates should learn to track their cycle, including ovulation windows, you can also calculate your ovulation date with other methods. Here are a few to discover.

Ovulation Predictor Kits (OPKs)

The most accurate way to know when you're ovulating is to use an ovulation predictor kit (OPK). These work by detecting a surge in luteinizing hormone (LH), which your body starts releasing about 36 hours before you ovulate. Because these kits give you the most advanced warning, they're your best bet for knowing when to time sex to coincide with ovulation.

Basal Body Temperature

Your basal body temperature (your body's temperature first thing in the morning) increases slightly—about 0.5 to 1 degree—when ovulation occurs. Because this spike is so small, you need a special basal body thermometer to measure it. A BBT thermometer is more sensitive than a regular thermometer and can detect temperature changes as slight as tenths of a degree.

Vaginal Discharge

Your cervical mucus can help predict your ovulation date as well. Most people have a clear and somewhat elastic, egg white-like (try stretching it between two fingers) discharge in the days leading up to ovulation.

Ovulation Symptoms

Some physical symptoms may accompany ovulation, but they're subtle enough that not everyone can spot them. About 40% of birthing people may experience lower abdominal pain (it's called mittelschmerz) when ovulation occurs. Breast tenderness is also a common sign of ovulation.

Ovulation Calculator

You can also try an online ovulation calculator, like the one below, to predict your fertile window. Keep in mind that results are just an estimate, but they can help you plan baby-making sex when trying to conceive.

Health Care Provider Visit

With blood tests and pelvic ultrasounds, a health care provider can monitor your ovulation cycle, says Jingwen Hou, MD, an OB-GYN specializing in reproductive endocrinology and infertility at Kaiser Permanente in Hawaii. A trip to an OB-GYN or health care provider's office can also help answer any questions about conceiving, including concerns about infertility, irregular menstrual cycles, and more.