How To Chart Basal Body Temperature: BBT Charting Made Easy

Sample BBT Chart

Homemade Basal Body Temperature Chart.
Homemade Basal Body Temperature Chart.

Basal Body Temperature Charting Fact Summary Sheet

  • Ovulation does not always occur on day 14 of your cycle. Day 14 is only an average. You may ovulate sooner or later (day 12 or day 20 for example)
  • To determine whether or not ovulation has occurred. Use the 3 over 6 rule. 3 consecutive higher temperatures following 6 lower temperatures.
  • There is a good chance of pregnancy if your temperature remains high, and you have not yet gotten your period by 18 dpo (days past ovulation).
  • Once you choose a method of checking your temperature (orally, vaginally or rectally), you must remain consistent throughout your cycle and use that same method every time.
  • Not everyone has a 28 day cycle. 28 days is only an average (some may be 26 days or 40 days for example).
  • Not all luteal phases are 14 days.
  • You must have at least a 10 day luteal phase to sustain a pregnancy.
  • The follicular phase is the first half of your cycle when your temperatures are generally lower.
  • The luteal phase is the second half of your cycle when your temperatures are generally higher. Occurring after ovulation.
  • Take your temperature at the same time every day.
  • Eating, smoking, and/or drinking can alter your basal body temperature.
  • BBT charting will only tell you if/when you have ovulated. Not when you are about to ovulate.

How To Chart Your Basal Body Temperature (BBT)

Basal body temperature charting ( BBT charting for short). Is used by many woman to help track and understand their monthly cycles. This technique is used for both trying to conceive and trying to prevent pregnancy.

It is both easy and can be done from your own home. You may use the "old fashion" way, like the pictures I have provided, and use a pen and paper. Or, thanks to technology, there are many apps and websites that you can use for your convenience.



Common Words Used With Basal Body Temperature Charting

Basal Body Temperature- Basal body temperature is the lowest temperature at which the body is at, at rest. To get an accurate basal body temperature. It is best to take ones temperature before getting out of bed. As any movement, food, drink, smoking, ect. can affect the results.

Follicular Phase- The Follicular phase of the menstrual cycle is the first half of the woman's cycle. A woman's basal body temperature is generally lower during this half compared to the second half, or, the Luteal Phase.

This phase begins on the first day of your period and ends the day you ovulate. When the Luteinizing Hormone is at it's highest point the ovaries are signaled to release the egg into the Fallopian tubes, therefore ending the Follicular phase and beginning the Luteal phase. It is the end of this phase that the woman is most fertile.

Luteal Phase- The Luteal phase is the phase in the menstrual cycle that begins the day after ovulation and ends the day before menstruation begins (the second half of the menstrual cycle). The average luteal phase is 14 days long. And must be at least 10 days long to support a pregnancy. A luteal phase shorter than ten days is called a "luteal phase defect".

During the luteal phase a woman's temperature will be slightly higher (about 0.4 degrees Fahrenheit or more higher) than the first half of the menstrual cycle. This is due to the corpus luteum producing the hormone progesterone.

The length of your cycle may vary from month to month. However, the luteal phase usually remains fairly consistent. It is the follicular phase that is changing, lengthening and shortening your cycle.

Luteal Phase Defect- A luteal phase defect is when the uterine lining does not become thick enough to sustain a pregnancy. This may be due to insufficient progesterone being produced, or the lining of your uterus is not using the progesterone properly.

This defect may cause your periods to show up earlier than expected, a short luteal phase, spotting between your periods and/or difficulty getting pregnant. It is best to speak to your health care provider if you suspect you are experiencing a luteal phase defect.

Menstruation- Menstruation is the loss of blood and tissue through the vagina from the uterus. Everyone month the uterus lining thickens to prepare for a pregnancy. If there is no pregnancy in the uterus, progesterone levels will drop and the uterine lining will begin to shed. Marking the first day of the menstrual cycle.

Days Past Ovulation (DPO)- Days past ovulation or dpo, begins the day after ovulation has occurred. This would be considered 1 dpo. Most menstrual cycles go all the way to 14 dpo and the woman should expect her menstrual period the next day (on average). If a woman makes it to 18 dpo and there has been no menstrual period and her temperatures have remained high. There is a high chance of pregnancy.

Cycle Day (CD)- Cycle day refers to what day of your cycle you are on. This may go from cycle day 1 right to cycle day 28 or more. Depending on how many days there are during your cycle before menstruation begins again. The term "cycle day" continues even after ovulation has occurred.

Ovulation Dip- Not all women experience an ovulation dip. However, some do and it helps them to recognize when ovulation has occurred. An ovulation dip is when the basal body temperature drops lower than usual on the day of ovulation. Then raises above the cover line and and remains there to confirm that ovulation has occurred.

Implantation Dip- Not everyone will experience an implantation dip. An implantation dip is a dip in temperature that may even dip below the cover line, around the time of suspected implantation (around 7-10 dpo). Although this dip does more commonly happen in pregnant cycles it does not necessarily mean that you are pregnant. Women sometimes experience a dip in temperature when implantation should be and then not end up pregnant.

Fallback Rise- A fallback rise usually occurs on 2 dpo (days past ovulation). Ovulation occurs, the basal body temperature rises the next day, and then falls again to or below the cover line the next. After this "fallback", the basal body temperature will once again rise at least 0.4 degrees above the cover line.

So Why Should You Chart Your Basal Body Temperature?


  • Charting can help you pinpoint ovulation. (Not everyone ovulates on day 14 of their cycle)
  • Charting can help you find your "fertile window" and increase your chances of becoming pregnant.
  • Charting can help you determine whether or not you are actually ovulating.
  • Charting can help you avoid any unwanted pregnancies by knowing and avoiding sexual intercourse during your fertile period.
  • Charting can help you determine whether or not there are any problems with your monthly cycle. Such as not ovulating, a luteal phase defect, ect.

Follicular Phase of BBT Chart

15 days of the follicular phase. Ovulation on cycle day 16.
15 days of the follicular phase. Ovulation on cycle day 16.

Luteal Phase of BBT Chart

Note: Not everyone experiences an ovulation dip (dip in temperature the day of ovulation).  Luteal phase shown with temperature jump of 0.8 degrees between follicular and luteal phase.
Note: Not everyone experiences an ovulation dip (dip in temperature the day of ovulation). Luteal phase shown with temperature jump of 0.8 degrees between follicular and luteal phase.

Implantation Dip on BBT Chart

Note: This picture is showing an implantation dip. Not everyone experiences and implantation dip.
Note: This picture is showing an implantation dip. Not everyone experiences and implantation dip.

End of Cycle BBT Chart

This BBT chart shows the cycle ending. Cycle day (cd) 30 or 14 days past ovulation (dpo) is the last day of the previous cycle. A temperature drop and the start of menstruation indicate the beginning of a new cycle.
This BBT chart shows the cycle ending. Cycle day (cd) 30 or 14 days past ovulation (dpo) is the last day of the previous cycle. A temperature drop and the start of menstruation indicate the beginning of a new cycle.

BBT Chart Showing DPO

This photo shows how days past ovulation works. It continues until menstruation starts.
This photo shows how days past ovulation works. It continues until menstruation starts.

BBT Chart Showing Cover Line

This photo shows how a cover line works. The cover line is drawn 0.1 degree above your highest follicular phase temperature.
This photo shows how a cover line works. The cover line is drawn 0.1 degree above your highest follicular phase temperature.

6 Days Under and 3 Days Over

This photo shows how to determine when ovulation occurred using the 6 days under the cover line and the 3 days over the cover line rule.
This photo shows how to determine when ovulation occurred using the 6 days under the cover line and the 3 days over the cover line rule.

Frequently Asked Questions Regarding Charting Basal Body Temperature


How Do I Go About Taking My Basal Body Temperature Temperature?

For best results, purchase a basal body temperature thermometer. These thermometers are usually digital and will read your temperature up to one tenth or one hundredth of a degree. You need a thermometer that will at least read to a tenth of a degree. As the bodies temperature may change less than one whole degree each day.

* You can still use a regular thermometer and be able to chart your basal body temperature. However, some state that these thermometers are not as accurate. While others have had no issues using them and determining ovulation. *

Choose a route in which you are going to check your temperature. Orally, vaginally or rectally will all give you a basal body temperature result. It does not really matter which route you choose to use (unless you are a mouth breather at night). As long as you are consistent throughout your entire cycle. Do not switch from vaginally to orally, ect. For example, if you choose to check your temperature orally, check it orally every day.


When Is it Best To Check My Temperature?

Only check your basal body temperature after you have had at least four hours of sleep. As the basal body temperature is the coolest temperature your body drops to while at rest.

It is best to take your temperature at the same time every day. Set an alarm if you need to. For every hour you sleep in, it is said that your body temperature raises slightly. Taking it at the same time every day will give you the most accurate result.

* However, if you are not able to take it at exactly the same time every day your results should still give you a fairly accurate ovulation reading. *

Take your temperature before you get out of bed for the most accurate result. Once the body is moving, or you eat, drink, smoke, ect. your temperature will change and the basal body temperature will not be as accurate. So keep a thermometer within arms reach from your bed.


Can Anything Mess Up My Temperatures?

Yes, there are a few factors that may give you inaccurate results.

  • Illness
  • Too cold or too warm of an environment
  • Taking your temperature at different times
  • Eating or drinking before taking your temperature
  • Smoking before taking your temperature
  • Too much movement before taking your temperature
  • Mouth breathing while sleeping


How Do I Chart My Basal Body Temperature?

You can make a paper chart or use a program on your computer or an app on your cellphone or other device. Take your temperature consistently every morning and do not forget to chart it. Do this everyday until menstruation begins. Menstruation is the first day of a new cycle. So a new cycle requires a new chart.


How Do I Know If/When I Ovulated?

Ovulation is often determined by the three over six rule. This means that you have had three consecutive temperatures 0.4 degrees or more above the past six temperatures.

For example,

(six days of low temperatures) CD (cycle day) 10 - 97.3 , CD 11- 97.2, CD 12- 97.4, CD 13- 97.3, CD 14- 97.3, CD 15- 97.4, CD 16- 97.4, (temperature shift of at least 0.4 degrees) CD 17- 98.2, CD 18- 98.1, CD 19- 98.3 (three days of an upward temperature shift of at least 0.4 degrees)

Ovulation then would be considered to have happened on CD 16 as it was the last day of the low temperatures. The next day being an upward shift of 0.8 degrees (more than 0.4) and remaining high for three consecutive days.

Pregnant BBT Chart

Temperature did not drop for 18 days past ovulation and menstruation did not show up. This is likely a pregnant cycle.
Temperature did not drop for 18 days past ovulation and menstruation did not show up. This is likely a pregnant cycle.

Do You Use BBT Charting?

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There's An App For That!

Here is a list of some apps for your phone or other device that you can use to easily track your menstrual cycle.

For The Android

  • Basal Body Temperature
  • Menstrual Calendar
  • Fertility Friend App
  • My Fertility Charts


For Apple

  • Kindara Fertility Tracker
  • BBT
  • BodyTemp and Period Monitor
  • Period View

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3 comments

Margery 2 years ago

That saves me. Thanks for being so sesbnile!


Julia 2 years ago

Hi Jenna!You might want to get a hormone pnneal run. If you do the blood test a couple days before you expect your period you can also validate if you ovulated. Looking at your charts there isn't clear signs of ovulation. The dotted line on FF indicates that there are some inconstancies between your temps and other fertility signs so you might be right.I know some doctors want to "wait" before running any tests but it doesn't make any sense to me. Your charts indicate irregularities and a hormone panel is a simple test to run. My Naturopathic Doctor ran thyroid, LH (should indicate if you ovulated), Progesterone, Estrogen, and a couple others I can't remember. I actually sought out my ND for TTC because I knew my PC physician wouldn't be very proactive and I didn't really want to get an OB/GYN unless I had to (I plan to use midwife during pregnancy and geeee just my luck my ND is also a midwife!). Hopefully your Dr will be open to running some basic tests.


Ivanildo 2 years ago

Temps should be taken at the same time every day, so even on the wekednes I set my alarm for 5am to temp, then I go back to sleep. Luckily my thermometer stores the last temperature so I don't have to worry about entering it until I'm awake.Oral temperatures didn't work for me because I sleep with my mouth open and I snore. I found that two temps would be drastically different even if I took one right after the other.TMI: I prefer vaginal temping because I can hit snooze, insert the thermometer and then take it out when the alarm goes off again. Before I fell asleep with the thermometer in my mouth multiple times. It's only slightly more inconvenient because I have to keep a pack of antibac wipes in my nightstand to wipe it down every morning, otherwise it grosses me out.

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