Everything You Should Know About Basal Body Temperature Charting

How to Track and Chart Your Basal Body Temperature to Get Pregnant

Basal body temperature charting is a popular method of ovulation detection and many women who want to get pregnant quickly try it out. Your basal body temperature is your body's temperature at rest. This is usually when you're sleeping, or first thing in the morning. 

How can you get started with basal body temperature charting? Can you tell if you're pregnant from looking at your chart? What else should you be charting, besides your temp?

All the answers are below!

Woman looking at a BBT thermometer
It's important you take your temperature first thing in the morning, before you get out of bed or even use the bathroom. GARO / Getty Images

There are so many advantages of charting your basal body temperature (BBT).

Charting can help you:

Your basal body temperature changes based on a number of factors, including your hormones. When you ovulate, the hormone progesterone causes your temp to rise. 

To know what your basal temp is, you must take your temperature in the morning before you get out of bed or move around. It's essential that you take your temperature correctly. Otherwise, you may not be able to detect ovulation. 

Here's how to take your BBT the right way for charting.


Paper BBT chart with temperatures marked
Your temperature on one particular day isn't important, it's a pattern of temperatures over many days. iStock

An individual body basal temperature taken on a single day won’t tell you much. 

You can’t tell if you’ve ovulated unless you look at the pattern of temperatures over a period of days and weeks. After you start charting, you'll notice that your temperature remains within a lower range for the first half of your cycle, and then shift upwards for the last two weeks. Ovulation—and the increase in progesterone—are what trigger that upward shift.

How can you detect ovulation on a BBT chart? Learn what you need to know about charting your BBT in this step-by-step tutorial.


Close up a woman holding a thermometer
They make special basal body thermometers, but you may not need one. Sigrid Gombert/Collection Mix: Subjects/Getty Images

Obviously, you need a thermometer if you plan on charting! Does it matter which one you buy?

There are thermometers made especially for tracking your body basal temperature, but you might not need one. A thermometer you already have at home may be good enough.

Ideally, you need one that is accurate to 1/10th (98.6) of a degree if you measure in Fahrenheit or 1/100th (37.00) of a degree in Celsius.

Here's what to look for in a BBT thermometer.


Woman looking intently at her basal body chart on her laptop
You can spend hours obsessing over your chart... try not to. Robert Warren / Getty Images

If you are a dedicated BBT charter, and you're not scouring the data for pregnancy clues, you are a rare woman.

At the start of the month, you likely spend days waiting for ovulation... and then—once you've unlocked that achievement!—you start looking for early pregnancy clues.

Are they in your chart to be found? Maybe yes. There are three primary ways to spot possible pregnancy in a chart: a triphasic pattern, an implantation dip, or 18 or more days of high temperatures.

Learn how your BBT chart can (and can’t) help detect early pregnancy.


Basal body temperature chart with ovulation and implantation dip showing
On this basal body chart, ovulation occurred on Day 15 and the implantation dip was on Day 23 (which is eight days after ovulation.). Rachel Gurevich

One BBT chart pattern that some say indicates pregnancy is an implantation dip.

It’s called an implantation dip because, according to the theory, your temperature will dip slightly when the embryo is implanting into the uterine wall.

Are implantation dips real? How do you know if you had one? Is it a reliable sign of early pregnancy? 


BBT (Basal body temperature) chart with triphasic shift illustrated
In this chart, the first temperature shift indicated ovulation on Day 15. Then, there is another temperature shift 10 days past ovulation. This is a triphasic pattern. Rachel Gurevich

Another envied BBT chart pattern is the triphasic chart pattern.

All BBT charts that detect ovulation are biphasic. This means there are two distinct levels of temperatures. The temperatures before ovulation are lower than the temperatures after ovulation.

With a triphasic chart, there is a third sustained rise in temperature, about a week after ovulation has been detected.

Could a triphasic chart be a positive sign towards pregnancy? It's more likely than with an implantation dip.


Woman coming out of the shower, where it's easy to check for fertile cervical mucus
If you get into the habit of checking your cervical mucus when you shower, it can be easy to add this info to your BBT chart. Ghislain & Marie David de Lossy / Getty Images

While your basal body temperature chart can show if you’ve already ovulated, it can’t tell you when ovulation is approaching. If you want to get pregnant, you need to have sex before ovulation—not after.

One way to make BBT charting more helpful is to also track the changes in your cervical mucus.

Some studies show that monitoring cervical mucus is a far more reliable way to time sex for pregnancy than BBT charting alone.

Find out how to check your cervical mucus here, and how to chart what you find here.


Woman looking at her BBT chart on her phone, confused
There are a number of possible reasons you can see fertile cervical mucus but not see a temp rise. PhotoAlto/Eric Audras / Getty Images

So, if all goes well, you should see fertile quality cervical mucus just before your basal body temperature rises. Egg white cervical mucus should indicate ovulation is just around the corner.

But what if you get cervical mucus, but don't see a temperature rise after?

There are a few possible reasons why...


Illustrations of cervical opening in woman who has given birth and who has never given birth
Your cervix changes based on where you are in your cycle. Morphart Creation / Shutterstock

Your cervix is pretty amazing. Another way to detect ovulation is by tracking how your cervix changes before ovulation. (And, yes, you can add this information to your chart.)

It’s not as common for women to track their cervical position, but it’s additional information that you can use to time sex for pregnancy.

If you're taking anti-histamines (which dries up fertile cervical mucus), tracking your cervical position can be particularly useful.

Learn how to check your cervical position and detect approaching ovulation.


Graph paper, pens, and glasses, ready to be turned into a BBT chart
Sure, you could track your BBT on graph paper by hand... but why?!. PhotoAlto/Odilon Dimier / Getty Images

Where are you going to write all these charting details down? 

There are dozens of free fertility charting websites and apps available. You don't need to get out your colored pencils and graph paper and do this on your own. (Though, you could if you wanted to.)

Here are the very best of the free fertility charting websites


Couple in bed about to have sex to get pregnant
Nature is smart. When you're most fertile, you and your partner feel more interested in having sex. Jamie Grill / The Image Bank / Getty Images

Depending on how detailed of a BBT chart you want to keep, you can write down all kinds of symptoms and signs that indicate ovulation. 

Other possible ovulation signs include:

Learn more about these ovulation signs here. (And here are five more ovulation symptoms, these more surprising!)


Woman sharing her basal body temperature chart to her doctor
If you're not ovulating, see your doctor. Bring your BBT charts with you!. Hero Images / Getty Images

One of the advantages of charting is you can see whether you are ovulating. If you're not ovulating, you can't get pregnant. If you are ovulating irregularly, it may indicate a possible infertility risk

Lack of ovulation is called anovulation and is a common cause of female infertility. Most women with anovulation can take fertility drugs, which will trigger ovulation and hopefully help them get pregnant. Clomid is the most well-known fertility drug used to treat anovulation.