Skip to main content

Detecting ovulation with a basal body temperature (BBT)

Detecting ovulation with a basal body temperature (BBT)

Seeing ovulation with a basal body temperature (BBT) chart is the most popular and effective way of trying to conceive (TTC).

A woman’s body temperature rises slightly during ovulation (the release of an egg from the ovary). This increase can be detected by taking your temperature every morning before getting out of bed.

There are many ways to chart your BBT, but the easiest is to use a special BBT thermometer that displays your temperature digitally.

 To chart your BBT correctly, you should take your temperature once in the morning before getting out of bed or eating or drinking anything.

Basal body temperature thermometer
Best Basal Body Temperature Thermometer Australia

What is Basal Body Temperature?

BBT is the average temperature of your body over 24 hours. When you’re ovulating, your body temperature will rise slightly. This change is called a rise in basal body temperature (BBT).

To take your BBT, you’ll need to use a basal body temperature thermometer. You’ll also need to record your temperature every morning after waking up and getting out of bed.

If you’re TTC and want to know when you’re likely to ovulate, you can use BBT charts as a guide. These charts let you see where your temperatures are on an average day and how they change throughout your cycle.

Choosing BBT Chart?

There are many different types of basal body temperature (BBT) charts. Some have bigger boxes, some have smaller containers, and some have more lines. Some even can track other factors like cervical mucus, vaginal discharge, and ovulation symptoms. However, the most common BBT chart is the one that has just one box per day. This kind of BBT chart will give you a visual representation of your body temperature over time and help you detect patterns in your cycle.

It’s important to use a graph with enough boxes for your cycle’s length (normally 28 days). If you’re not sure how often you ovulate, start by charting for at least two months before trying to detect ovulation with a BBT chart.

Why Chart BBT?

Measuring BBT is a great way to track your ovulation. BBT is your body’s temperature at rest, taken first thing in the morning before you get out of bed. A slight increase in BBT is one of the earliest signs of ovulation.

To measure BBT, use a special thermometer purchased at any pharmacy or drugstore. Most digital thermometers will work fine, but try not to use one that has been used by someone else, and make sure it’s very clean before using it on yourself (a mouthwash rinse or swab with rubbing alcohol works great).

The ideal method to take your temperature is by inserting the thermometer into your rectum (not vagina) before getting out of bed in the morning. Be sure to wait until your body has had time to settle down for about 15 minutes after waking up. It can be difficult if you have small children waking up early, but try your best! Once you’ve inserted the thermometer, please leave it in place for at least three minutes to get an accurate reading.

You may find that taking your temperature every day can be tedious and time-consuming — especially if you have irregular periods. However, there are some apps available.

Tracking ovualtion using a BBT
Image courtesy of The Bright Girl Guide by Demi Spaccavento.

How to Measure Basal Body Temperature?

To measure basal body temperature (BBT), you need a basal body thermometer. These special ovulation thermometers are available online and are inexpensive. You can also use a regular, store-bought digital thermometer, but it’s harder to read the number on a digital screen, and the accuracy may be less than with a traditional mercury thermometer.

Once you have your thermometer, record your temperature upon waking each morning before getting out of bed or doing anything else. The reading you will record is called your waking temperature. Check your BBT every day until you get a pattern established.

Once you have learned your normal waking temperature (it should be between 35.55 and 36.66 degrees), chart how high or low it rises each day, depending on whether ovulation has occurred. You will notice that it rises significantly higher than any other time during your cycle when you ovulate.

Steps to measure BBT

Below are some steps to follow when measuring BBT:

  •  Take your temperature as soon as you wake up.
  • Use a basal thermometer and take the temperature under the tongue or in the mouth, not on the cheek or next to the gumline.
  • Make sure you take it simultaneously every day (before getting out of bed, after urinating, and before eating).
  • Record your temperature in a notebook or on an app (such as Fertility Friend or Kindara) each morning for several months (at least three) during your cycle to see if any patterns repeat themselves over time.

When to Start Charting Basal Body Temperature

The key to charting your basal body temperature is to set a baseline for yourself. You should start at the beginning of your cycle and continue to record your BBT until you get pregnant or until you decide that you want to stop trying.

Once you’ve determined when you ovulate, please record it by writing down the day of the month that it happened and how long it took after your period ended. When you do this consistently, you’ll be able to determine if the length of time between ovulation and menstruation changes over time.

It might indicate that your periods are becoming more regular if it’s getting shorter. If it’s getting longer, this may mean that you are becoming less fertile. It can be useful information if you’re trying to conceive or avoid pregnancy.

Charting BBT
Charting BBT can help predict ovulation.

Identifying Ovulation

Ovulation is when an egg is released from a female’s ovaries and is one step in the menstrual cycle. Ovulation occurs around the middle of your menstrual cycle i.e day 14 of a 28-day cycle.

On average, a menstrual cycle is 28 days long, but every woman’s body works differently. Your menstrual cycle may be quite significantly longer or shorter than 28 days, meaning that your ovulation period may differ. 

You can detect ovulation by tracking your basal body temperature (BBT), which is your body’s temperature at rest. The temperature rises after ovulation due to an increase in progesterone hormone levels. 

Your BBT will remain increased for several days after ovulation until it drops again towards the end of your cycle. By charting this change over time, you can determine when you’re likely to ovulate each month, allowing you to know when conception (fertilization) is most likely to happen. 

Getting Pregnant

There are many ways to get pregnant. Some people know when they’re ovulating, while others don’t. If you’re trying to conceive (TTC), then you’ll want to make sure that you know exactly when your body is ready for conception.

You can track ovulation and fertility using several methods, but a basal body temperature chart is one of the most popular methods.

The basal body temperature is the lowest in your body during sleep and is directly impacted by your hormones. The higher your basal body temperature (BBT) during ovulation, the better chance you have of getting pregnant.

If you’re TTC naturally or through IVF, learning how this method can help you achieve pregnancy will be a huge benefit.

Other Things to Track Besides Basal Body Temperature

It’s important to track other things besides your basal body temperature. For example, you should also be monitoring your cervical mucus and your cervix position.

Cervical Mucus

Cervical mucus is a great tool for helping you identify fertile days. It changes throughout the month, becoming more slippery and stretchy as ovulation approaches. The mucus can be clear or cloudy, and it often resembles raw egg whites. It is called ferning and indicates that you’re ovulating soon.

Cervical Position

You can also use your cervix position as an indicator of fertility. When you’re fertile, your cervix will feel soft, low, and open, similar to the feeling of the tip of your nose so that it can accept sperm easily during intercourse. If you feel this way during sex, it’s a good sign that you might be ovulating soon!

Days you Have Sex

If you want to get pregnant, it’s best to have sex on the days around ovulation. You can use an over-the-counter ovulation predictor kit (OPK) or monitor your cervical mucus (CM) if you think you’ve already ovulated and aren’t sure when that happened.

Mood Swings

During ovulation, hormones are at their peak levels in your body. It can cause changes in moods during that time, which means that even if you’re not trying to conceive right now, tracking these changes could still be helpful if you want a baby someday!

Ovulation Predictor Kit Results

If you are using an OPK, it is important to record your results in a chart or calendar. It will allow you to compare them with your BBT chart and determine if they were accurate or not.

PMS symptoms

Some women experience PMS symptoms during their fertile window, so if these symptoms start to appear around the same time every month, they may indicate that ovulation has occurred.

Tracking basal body temperature
How Do You Use a BBT Chart to Pinpoint Ovulation?

When not Ovulating

If you’re not ovulating, the next step is to find out why.

If you’re trying to get pregnant, it can be frustrating to see all of your friends getting pregnant and posting about it on Facebook. But if you’ve been trying for a year or more with no success, ask yourself some questions:

Are you ovulating? You can test this by charting your basal body temperature (BBT) each morning before getting out of bed. You can either use a special BBT thermometer or track it on an app. (There are tons of free ones online.) For the first couple of months, try to take your temperature first thing in the morning when you wake up before moving or eating anything. Once you have enough data points, plug them into an online calculator that will tell you when you ovulated (or didn’t).

Is there something wrong with my partner? Your partner might be suffering from low sperm count or other issues that would prevent pregnancy. Talk to your doctor about options like artificial insemination or IVF treatment.

Pregnant Basal Body Temperature Chart

This Pregnant BBT Chart is a useful tool that helps you keep track of your basal body temperature while you’re pregnant. In addition to serving as a convenient calendar, it provides recommendations on when to abstain from Sex, schedule an appointment with your doctor, and share your results with family members.

There are four ways a BBT chart can indicate a pregnancy:

A persistent increase in temperature 

A sustained rise of at least 0.1°C above the pre-ovulatory temperature, lasting for at least three days, is considered a positive confirmation of pregnancy.

A sustained drop in temperature 

A persistent fall of at least 0.2°C below the pre-ovulatory temperature, lasting for at least three days, is considered a positive confirmation of pregnancy.

Steepening slope

A steepening slope between two temperatures indicates possible implantation. It is considered promising evidence of pregnancy if other signs are also present. However, it does not conclusively prove that conception has taken place because it may result from other factors such as fever or illness.

Uterine changes

An ultrasound scan can detect changes in uterine size and shape as early as six weeks after conception; these changes may be apparent up to eight weeks after conception, with an experienced examiner catching them earlier.

Start-Up fertility kit
Buy ovulation thermometer Australia.

Benefits of Basal Body Temperature charts

The benefits of using BBT charts include:

  • Accuracy: BBT charting is very accurate. The temperature method uses your body to measure fertility, and can you can use it if you do not want to use hormones or other forms of birth control. This method is more accurate than other methods because it considers your fertility cycle, which varies from woman to woman.
  • Convenience: You do not have to take any action before intercourse, such as taking a pill or putting on a condom. The only thing you need to do is record the temperature every day in your menstrual cycle and then look for patterns to identify when ovulation occurs. However, this may not always be possible if you have irregular cycles because there are not enough data points for an accurate reading.
  • Cost-effective: You can use BBT thermometers for years without buying new ones. However, they should be properly cared for and cleaned after each use. And since there are no chemicals involved with these devices, they are safe to use.

Contact us For More Information!

Understanding your body is the first step in learning to track ovulation. Your basal body temperature (BBT) chart, which measures your body temperature at rest, can be an important tool for tracking ovulation.

You should take your temperature each day and record it on a fertility chart. Knowing how to identify key signs of ovulation might help you conceive faster or avoid an unplanned pregnancy using contraception.


Monitoring your basal body temperature can be a great way to predict ovulation. Buy an Australian BBT thermometer for the best results