Ovulation Calculator: Find out when you're ovulating

Knowing your body and understanding your menstrual cycle can help you determine when your most fertile days are and increase your chances of conception.

This article explains how an ovulation calculator works and how it may help your family planning journey.

How do I use the ovulation calculator?

RMA's ovulation calculator is a valuable tool for women who want to track their menstrual cycles and determine when they're most fertile. To use it, enter the first day of your last menstrual period and the average length of your menstrual cycle. (Your cycle length is the number of days between the first day of your last period and the start of the next period.)

Once you've entered this information, the calculator will generate a calendar displaying your estimated ovulation days for the next several months. It's important to note that this is just an estimate and should not be used as a sole method for contraception or fertility planning.

Select the first day of your last period


What if my periods are irregular?

An irregular menstrual cycle can make it difficult to predict ovulation using a calendar-based method.

Examples of an irregular menstrual cycle include:

  • Cycles that are shorter or longer than the average (21-35 days)
  • Unpredictable periods
  • Inconsistent cycle lengths

Other signs of an irregular period include:

  • Missing three or more periods in a row
  • Heavier or lighter flow than usual
  • Periods that last for seven days or longer
  • Bleeding or spotting between periods

Important note: Everyone's body is different, and cycles vary from person to person. What's "normal" for one person may not be the same for another.

If you think you have an irregular cycle, there are other ways to determine whether you're ovulating, including changes in cervical mucus and tracking your basal body temperature (BBT).

Ovulation predictor kits (OPKs) may also be helpful, but they're not foolproof and can sometimes give false positives or negatives.

How your fertile days are calculated

The average menstrual cycle length is 28 days, with ovulation typically occurring on day 14. Ovulation calculators use this information to predict your ovulation date or the day that you're most fertile.

Ovulation calculators work by counting back 14 days from the expected start of your next period. This is known as the fertile window and includes the day of ovulation and five days before it.

Ovulation calculators provide a general estimate of when a person will ovulate, but it’s important to remember that this number is just an estimate. Other factors, such as stress, illness, and certain medications, can affect the timing of ovulation.

To get a more accurate picture of your fertility, it's a good idea to use a backup method to track your fertility and to pay attention to your body's other signs of ovulation.

Signs of Ovulation

Not every person experiences ovulation the same way, but there are a few common ovulation symptoms to watch for:

  • Cervical mucus changes. Cervical mucus (fluid from the cervix) changes throughout the menstrual cycle. Around ovulation, it becomes clear, stretchy, and thin. This type of mucus is most conducive to sperm transport.
  • Breast tenderness or soreness. Some people experience breast tenderness or soreness around ovulation.
  • Pelvic or lower abdominal pain, cramping, or bloating. Mild cramping, or mittelschmerz, is a common sign of ovulation.
  • Spotting or brown discharge. Some people experience light spotting or brown discharge around ovulation.
  • Changes in sex drive. Some people may notice an increase in sex drive around ovulation.
  • Nausea and headaches. Less common signs of ovulation include nausea and headaches.
  • Basal body temperature (BBT) changes. BBT is the lowest body temperature that occurs during rest. It goes up a bit after ovulation. Tracking your BBT can help you figure out when you're ovulating and when you're most likely to get pregnant.


Here are the answers to some frequently asked questions about ovulation and the best time to conceive:

When do you ovulate?

In an average 28-day cycle, ovulation usually occurs around day 14. However, only 30% of women experience ovulation between days 10 and 17. Most reach their fertile window earlier or much later.

How to know when you're ovulating

One of the most common signs of ovulation is changes in cervical mucus. This fluid will start sticky and white and gradually become clear, slippery, and stretchy like raw egg whites.

Another sign of ovulation is increased basal body temperature (BBT).

Some people may also have a heightened sense of smell or changes in appetite or mood.

When is the best time to conceive?

There are only six days within the menstrual cycle where pregnancy is possible — the five days leading up to ovulation and the day of ovulation itself. This is called the "fertile window," and it represents your most fertile days.

Sperm can survive in the female reproductive tract for up to five days, so having sex anytime within the fertile window increases the chances of conception.

According to the American College of Obstetricians and Gynecologists (ACOG), couples should aim to have sex every day or every other day during these six days.

Speak with Our Fertility Specialists

At RMA, we understand that starting a family is an emotional journey, and we're here to support you every step of the way. Our fertility specialists are experts in their field and are passionate about helping aspiring parents make their dreams of having a child a reality.

If you're in the family planning stage and want more information on ovulation or how to increase your chances of conception, we're here to help. We're also here to provide the emotional support and guidance you may need throughout your fertility journey.

Ready to take the next step? Give us a call or fill out our contact form to schedule a consultation with one of our fertility specialists.

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