How to Predict Ovulation with a Basal Thermometer


Ovulation is the most fertile time in a woman’s monthly cycle. If you’re trying to conceive, it’s important to know when you’re ovulating, so you can improve your chances of getting pregnant. While there are many ways to predict ovulation, one of the most popular and affordable methods is a basal thermometer.

[Read more about Ovulation]

What is a Basal Thermometer?

A basal thermometer looks just like a regular thermometer, but it’s capable of detecting subtle changes in body temperature. These thermometers are very sensitive and can measure temperature changes much more closely than an ordinary thermometer.

A basal thermometer is designed to measure your basal body temperature (BBT), or your body’s temperature when you first wake up in the morning.

Why is your body temperature important? When ovulation begins, an increase in the progesterone hormone will cause a slight increase in your basal body temperature. This increase in your body’s temperature will last until your next period. The purpose of this temperature rise is to create a warmer, fertile environment for sperm.

The only practical way to detect this slight change in temperature is with a basal body thermometer.

Digital basal thermometers are the most popular choice, and they offer a number of helpful features. These include:

  • Memory recall: Each time you turn on the thermometer, it displays the last recorded temperature.
  • A beep when the reading is complete: Many thermometers will beep when they are finished reading your temperature.
  • Accurate within 1/10th or 1/100th of a degree: In the very least, a basal thermometer will be accurate within 1/10th of a degree, which is ideal for fertility charting.

[Read more about Progesterone]

How to Take Your BBT

The woman is taking her BBT in the bed.

To get an accurate reading of your BBT, you need to take your temperature early in the morning, before you get out of bed. Why? A basal thermometer measures your body’s temperature when it’s at rest. Even the slightest of movements can increase your temperature and skew your reading.

Be sure to take your temperature at the same time each morning. Again, it’s important not to move or even sit up before taking your temperature. Otherwise, your results may be inaccurate.

A basal thermometer can be used to take your temperature orally or vaginally. Either method is fine, but you will need to be consistent with which method you choose. If you decide to take your temperature orally, you should continue to do so the entire time you are tracking your BBT.

Charting Your BBT

Monitoring your BBT in a fertility chart can help you determine when you’re ovulating and which days to have xxx. You will be most fertile on the first day you notice a spike in your temperature, and the few days before ovulation.

A sample of charting BBT.

The first few months of charting will tell you when you have ovulated, which will help you pinpoint a pattern. Once you have identified a pattern, you can predict your most fertile days each month.

To begin your chart, start on the first day of your menstrual cycle. Write down your BBT temperature on your fertility chart or calendar. Many basal thermometers come with a fertility chart for your convenience.

Some women experience a gradual rise in temperature. For others, the rise is sudden. A temperature rise of 0.4 to 0.6 degrees is a good indication of ovulation.

A thorough, detailed fertility chart can help you predict your best window of opportunity for conception.

[Read more about Fertility]

Factors that Affect the Accuracy of Your Reading

Obtaining an accurate reading of your basal body temperature can be difficult. There are many factors that can affect the accuracy of your reading and skew your results one way or the other.

  • Illness: If you are ill at any point during your charting, this can affect your readings. If you’re running a fever, your body temperature will naturally be higher and may throw off your chart. While you should still chart your temperature during this time, it is also important to note that you were ill during the time of the reading.
  • Movement: Sitting up or standing up will cause your body’s temperature to rise naturally. To achieve the most accurate BBT reading, take your temperature as soon as you open your eyes in the morning and before you even sit up.
  • The wrong equipment: A traditional thermometer is not sensitive enough to detect slight rises in body temperature. To get a truly accurate reading, you will need a basal thermometer.
  • Lack of sleep: You must get at least four hours of sleep before you can obtain an accurate BBT. If your sleep is interrupted in the hours just before waking, this can cause inaccurate readings.
  • Certain medications: Some painkillers can lower your body temperature. Other medications may either increase or lower your body temperature and skew your results.

Monitoring your BBT can be an accurate way to predict ovulation providing you take your temperature properly and with a basal thermometer.


  1. Am trying to get pregnant again with my second child for my fiance for some months now but is like something wrong my period kept coming regular an irregular at times wat can I do to solve all this plz some reply


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