When Do You Ovulate: Facts on the Ovulation Cycle

There's a lot to know about the ovulation cycle. We're here to help.

Digital thermometer on a green background
Photo: malerapaso/Getty Images

Textbooks make it sound so straightforward: Ovulation happens in the middle of your cycle, which is 14 days before the start of your next period. So if you have a dependable 28-day cycle, you ovulate on the 14th day. But people with ovaries aren't textbooks, and in reality, many of our cycles vary from month to month. As a result, whole industries have sprung up to help you figure out when you might be ovulating.

Some people like a DIY approach that involves getting to know their body really well; others prefer kits that do the job for them. Either way, it helps to know more about what's going on in there and why, and what all your options are for knowing when you're ovulating and when your most fertile days are.

What Is Ovulation?

Your ovaries hold thousands of eggs, and ovulation happens each month when your hormones tell your ovaries to release a mature egg down the fallopian tube.

What Is the Difference Between Ovulation and Fertile Days?

Ovulation is an event—the releasing of the egg. Fertile days are a window. Your most fertile days are the 5 days before ovulation or the day after. That's because sperm can survive in your body for three to five days. While an egg only survives for about 24 hours after leaving the ovary, sperm can be waiting around for it to be released. So sex up to five days before ovulation still gives you a chance of conceiving.

Your Likelihood of Conceiving

Ovulation Chart

When Do You Ovulate?

Not every person with ovaries ovulates exactly 14 days before the day their next period starts. Cycles are different lengths, so a good way to think about it is that you're likely to ovulate four days before or after the midpoint of your menstrual cycle.

But don't just depend on the calendar to figure it out (that can be frustrating if your periods are irregular). Pay attention to the signs and symptoms of ovulation to get insider info on when the egg is being released. Or, rely on technology and commerce and purchase an over-the-counter kit at the drugstore to help you out (see below for more information on those).

How Long Does Ovulation Last?

Ovulation—the actual process of your ovaries releasing an egg—doesn't take long; about 12 to 24 hours. But remember that your fertile window is open a lot longer than that. So if you're trying to get pregnant, don't panic that you have to jump into bed during those exact 12 to 24 hours that you're ovulating. Sperm can be in your body, waiting to meet and greet the egg, for three to five days beforehand.

Signs and Symptoms of Ovulation

The signs of ovulation are nowhere near as obvious as your period. In addition, says endocrinology and fertility expert Rashmi Kudesia, MD, consultant for HealthyWomen.org, "not everyone gets all the different signs." So if you want to take a DIY approach to estimating when you're ovulating, you need to tune into your body and pay attention to your body temperature, your cervical mucus (what you call discharge), and the feel of your actual cervix. In addition, some people feel a little twinge in their lower bellies when their ovaries release the egg (that pain is known as Mittelschmerz). Here's what to look for:

Symptom #1: Changes in Your Basal Body Temperature

Most people's bodies are 96 to 98 degrees F. Ovulation may drive up your body temperature a half to one degree. So you're not going to notice this change without a really good thermometer and without knowing your individual normal body temperature (measured first thing every day, before you get out of bed).

Symptom #2: Changes in Cervical Mucus

Just before ovulation, you'll have more cervical mucus, and it will be thin and slippery ("like egg whites," some experts say). After ovulation, it becomes thicker and less noticeable. If you want to get pregnant, the days mucus is thin and slippery are your best bet. The challenge: "Not everyone has a lot of cervical mucus," Kudesia says, so this method is less likely to be useful if you're in that group.

Symptom #3: Changes in your Cervix

As you approach ovulation, your cervix actually changes; it dilates and feels a little soft, like your lips. Afterward, it feels harder, like the tip of your nose. This isn't a main way to know you're ovulating—it's subtle, and it's not exactly convenient to try to reach all the way up to your cervix and touch it every day. But if you want to be ultra-familiar with your body, this can give you interesting clues to when ovulation occurs.

How to Predict Ovulation

There's no single perfect way to predict ovulation (or else far fewer people would be frustrated that they're not getting pregnant). There are many ways to estimate it, and which you choose depends on how much you want to get to know your body, and how much you'd rather just spend money on a kit that can tell you (of course, you can do both). Ovulation is usually easiest to predict if you have a regular cycle.

Of course, if you've been estimating your ovulation cycles for a while and not getting pregnant, it's worth seeing a doctor. "None of these methods are foolproof," says Kudesia. "I've seen people come in with regular cycles who were trying to get pregnant for years, and then we find out they're not ovulating. It turns out to be much more complex than we'd like it to be." Nonetheless, for many people, these ovulation prediction methods can be helpful or even right on.

Method #1: Basal Body Temperature Monitoring

When you ovulate, your body will be a little warmer—but not much. Your basal body temperature—meaning your basic body temperature before you do anything at all—goes up by a half to one degree. When your temperature goes up, it indicates that you're ovulating. Note: It's not telling you that you're going to ovulate, it's telling you that ovulation is happening right now.

To use basal body temperature as a tool, you need to keep a careful calendar of your daily temperature, and you need to be really on it about taking your temperature right.

Measure your temperature every day before you get out of bed (no peeing, talking, checking your phone or brushing your teeth first). Be aware that to measure the tiny changes in body temperature, a special basal thermometer (available at most drugstores) is required. Keep the thermometer in place for about five minutes, and then record what it says. You need at least a few months' data before you start seeing patterns that help you understand when you're likely to be ovulating.

"People are of mixed minds about how useful this is," Kudesia says, since by the time you can see the temperature spike, it's too late to do much about it other than chart it and look for patterns in the future. That said, "some people like tracking and find it really empowering to be this attuned to their bodies," she says.

Method #2: Cervical Mucus Method

To help figure out when you're ovulating, keep a chart of what your mucus is like each day and look for patterns over a few months. Every day, write down whether mucus is noticeable and what it's like. Record whether it's thin and slippery, sticky, cloudy, or if there's none.

When your records show it's thin and slippery and the amount noticeably increases, that's an indicator that you're ovulating. If you want to become pregnant, experts recommend trying every day or every other day when your mucus is like this. If your body just isn't one that produces a lot of discharge, it's going to be harder for you to determine much about when you're ovulating from this method.

Method #3: Menstrual Charting/The Calendar Method

Plenty of great apps help you track your menstrual cycle, but you can easily do it with pen and paper, too. To figure out when your most fertile days are likely to be, write down the first day of your period for a few months in a row. Count how many days there are between them. That's the number of days in your cycle. Keep track of how many days are in your cycle over six months. For many, the number of days is different for almost every cycle.

To predict your most fertile days (this only works if your cycle is 27 days or longer), find the shortest cycle. Subtract 18 from the number of days in that cycle (so if it was 26, your new number is 8). Now go back to your calendar and find the first day of your most recent period. Call that day one, and count 8 days forward from that. Mark an X on that day. That's your first fertile day.

Then find the last likely fertile day: Find the longest cycle. Subtract 11 from the total days in that cycle. Call the first day of your most recent period day one, and count forward 11 days. Mark an X to indicate your last fertile day.

However, this method is not foolproof, and it's most effective when used with other methods for knowing when you are ovulating, like checking your basal body temperature and cervical mucus.

Method #4: Ovulation Kits

Ovulation test kits are a little bit like pregnancy tests—with the most common ones, you pee on a stick and the test checks for a hormone called luteinizing hormone (LH); the surge in that hormone is what causes ovulation to happen. This type of ovulation test doesn't tell you that you've ovulated; it just tells you that your body is asking your ovaries to release an egg, and it's likely to happen in the next 24 hours.

Some newer tests check your saliva for increased estrogen, but the FDA warns that the tests can be finicky; they can be thrown off by simple things like drinking or how you put your saliva on the slide.

Method #5: Fertility Monitoring

Fertility monitors sound scarier than they are. They're simply devices that read your hormones (sometimes they measure a type of estrogen as well as LH), most commonly via a stick that you've peed on. They're designed to tell you your most fertile window. Some tell you which days to take the test, and they come up with a reading on whether it's a high, low, or peak fertility day, so you get more information to act on than you would with a simple ovulation kit.

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