Blank BBT Chart & Instructions to Detect Ovulation

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Learn how your temperature changes during your cycle and how you can use this information to detect ovulation.

Your basal body temperature is the lowest body temperature attained during rest, usually after sleep. Approximately one to two days after ovulation, a woman's BBT will rise slightly and stay higher for at least 10 days. You can record your BBT to accurately detect if you ovulated and you can use this information to help predict future ovulations and I'll be explaining exactly how you can do this.

First, let us understand why there is a change in BBT during the cycle

The same hormones that control the phases of the menstrual cycle are responsible for raising BBT. Prior to ovulation during the follicular phase, higher levels or estrogen lowers BBT, then after ovulation during the luteal phase, higher levels of progesterone raise BBT.

So, how do we accurately detect ovulation by our BBT?

Get yourself an accurate digital thermometer, one that can measure to the tenth of a degree. For example, it can measure to 98.4F instead of just 98F. There are different types of thermometers available, some may have a memory recall feature, or beep to indicate that the the reading is finished, but the most important thing to check is "can it measure to one tenth of a degree"?

You are going to be taking you temperature everyday, so please ensure you know how to use your thermometer to get an accurate reading. Read the directions carefully. For example learn what the beeps mean or how long to leave it in if it does not beep.

Download Blank BBT Charts

Before we begin the steps, decide if you are going to log your temperatures into Ovulation Calculator online via your phone or use one of our blank BBT charts below, click Celsius or Fahrenheit below to download.

Steps to measure your BBT accurately

  1. Leave your thermometer, pen, chart or phone on your bedside table.
  2. Take your temperature everyday at the same time, immediately after waking, before any activity, including even sitting up. You can set an alarm to make sure it's the same time each day.
  3. Take your temperature in your mouth. Insert the tip of the thermometer under your tongue and push it toward the back where the tongue meets the bottom of the mouth. Leave it there long enough to get an accurate reading.
  4. Log your temperature into your chart by marking a cross (x) in the box that corresponds with both the temperature and the cycle day; or
  5. Log the temperature into Ovulation Calculator via your phone if you are using our website to predict when you're fertile.
  6. Repeat every day.
  7. Make a note of any disturbances such as fever, stress, alcohol the night before, so that you can take this into account when analyzing your cycle (more on this below).

Here's a sample of a basal body temperature chart:

Sample bbt chart

Using the results to detect when you ovulated

Your BBT will rise slightly after you ovulate (see above sample), only by about 0.5 to 1 degrees Fahrenheit (about 0.3 to 0.5 degrees Celsius). Look for the temperature rise on your BBT chart. Your fertility reaches it's peak two to three day BEFORE your temperature rise.

Predict future ovulations by using the following formula

  1. Count the number of days from the temperature rise to the day before your next period.
  2. Add two to this number (we add two because the rise is approximately two days AFTER ovulation).
  3. Deduct the number from your average cycle length.

For example, if your average cycle length is 30 days and the number of days between your BBT rise and day before your next period was 11, you would add 2 to 11, to give you 13 (estimated ovulation day was 13 days before your next period). Then you would deduct 13 from 30 (your cycle length) which would give you 17. Your estimated day of ovulation is cycle day 17.

Ensuring you get accurate BBT readings

When you first start out monitoring your BBT it can be a little confusing. However, do not be concerned as it is typical for it to take a little while to get the hang of it never mind actually understanding what your temperature is telling you.

Despite your best intentions there are a number of factors that can affect your BBT and give you either a higher or lower than normal reading. These include:

- A late night
- Broken sleep
- Oversleeping
- Alcohol the night before
- Some pain relief medications
- Illness or fever
- Stress
- Drugs
- Travel
- Time zones
- Shift work
- Change of room temperature
- Breastfeeding

Following our advice on how to get an accurate reading will really help you to understand your cycle and identify when you are most fertile. Inevitably, normal life will sometimes get in the way and it is very difficult to prevent factors like stress or illness for example, from interfering with your recordings. So, in addition to the steps above, see the following to improve the accuracy of your readings:

  1. Check your thermometer regularly for any breakages and do not forget to replace the batteries regularly. If you do need to buy another thermometer, start using this at the beginning of a new cycle. If you need to use it sooner, make a note of when you did this incase the baseline reading changes.
  2. Try and keep your room at a constant temperature at night to avoid fluctuations in temperature due to your environment.
  3. Try to get at least three hours of uninterrupted sleep before taking your temperature at the normal time.
  4. When taking your temperature make sure you leave the thermometer in place for the required time.
  5. Try not to skip taking any readings, as this will not give you an accurate picture of your fertility for that cycle.
  6. Use a thermometer with a memory facility if you do not want to record your reading straight away. You can then fall back to sleep and record the reading when you get up to start your day.

Taking your BBT is easy and gives you helpful information about your cycle and your fertility.

Watch the video

Dr. Tash, leading fertility expert explains how to accurately chart your basal body temperature (BBT) to identify ovulation to learn when you are fertile.

Share your results and discuss your BBT with others or ask a question. Leave a comment below.

New Join the Discussion!

  1. Stella Aug 03, 2016
    I am grateful to God Almighty for allowing me be a part of this community. I never knew the importance of BBT until now. Thanks, Dr. Tash.
  2. Esther Aug 15, 2016
    I am so happy about this information. I will try and get a thermometer.
  3. Elfrida Aug 16, 2016
    Thanks, this is very useful information. I have yet to get a thermometer, but I would love to try this.
  4. Louise Aug 16, 2016
    Thank you so much for everything. I understand better now.
  5. Valerie Aug 17, 2016
    So if your tempature is high for 18 days, you're not likely to be pregnant?
    1. Christina (OC Team): Charting BBT is very effective for learning when you ovulated, but it unfortunately is not a reliable way to determine whether implantation occurred. - (Aug 17, 2016)
  6. Nyla Aug 19, 2016
    I can feel the rise in temp from mid cycle to my next period. Especially my thighs feel so warm.
  7. Kekong Aug 22, 2016
    Well, I think there is truly a rise in my temperature because my ovulation started yesterday and my temperature rose the day before. My hands and feet feel warm.
    1. Christina (OC Team): Even if you feel the rise in your body, it's best to track with a thermometer. Good luck! - (Aug 22, 2016)
  8. Kekong Aug 22, 2016
    Where can i find the thermometer and what will I tell them I want to buy?
    1. Christina (OC Team): You can use any thermometer that gives readings to a tenth of a degree. For example, 98.6. Digital thermometers are easier to read, so you probably want to go this route. Good luck! - (Aug 22, 2016)
  9. Odunze Aug 28, 2016
    In July, I had my period on the 8th. My last period was on 4th of August. Then I had intercourse with my husband on the 16th,17th, skipped the 18th, and I had sex again on the 19th, 20th, 21st. Will I be pregnant?
    1. Christina (OC Team): If those dates are within your fertile window, you have a chance at conceiving in this cycle. Log your information into your account here to get a prediction of your fertile window. Good luck! - (Aug 28, 2016)
  10. Odunze Aug 29, 2016
    I am presently menstrating, which started on 28th August. Which dates are in my fertile window?
    1. Christina (OC Team): Log your cycle dates into your account here to get a prediction. You'll need to know the start and length of your cycle. - (Aug 29, 2016)
  11. Odunze Aug 31, 2016
    The length of my cycle is usually 26, and sometimes it is 28 days.
  12. Karen Sep 01, 2016
    This month is my first to chart BBT. My cycles being 25 days, it showed I ovulated cd11, which was august 19. I slept with my dh on the 14,15,17
    1. Christina (OC Team): If you ovulated on the 19th, then you had sex within your fertile window and have a chance at conceiving. Good luck! - (Sep 01, 2016)
  13. Salomey Sep 07, 2016
    This is very useful information. I use to have thermometer and I didn't know how to use it, although I recorded my temperature every morning. I need to look for it and start using again. This is the exact information I was looking for some time ago. Thank you.
    1. Christina (OC Team): So glad you found it helpful. Good luck on your journey! - (Sep 08, 2016)
  14. Aminat Sep 12, 2016
    I really appreciate this information.
  15. Valerie Sep 12, 2016
    Christina, so my husband and I BD on the 7th. I had ovulation bleeding on the 8 ,9 and 10th. I actually ovulated on the 10th, according to my tracking. Now we BD on the 11th. Do you think I have a chance of conception?
    1. Christina (OC Team): If you actually ovulated on the 10th, the 11th would have been outside of your fertile window and the 7th would have been within. So you would have a chance. It does only take one sperm, after all! Good luck! - (Sep 12, 2016)
  16. Thonia Sep 24, 2016
    Hi, according to my calculation, my fertile days were from the 19th-24th. I had sex with my hubby on the 23rd and 24th. What are my chances of conception? And when can I do a pregnancy test? Thanks.
    1. Christina (OC Team): You had sex within your fertile window, so you have a chance to conceive this cycle. You can test on the 8th. Good luck! - (Sep 24, 2016)
  17. Hadijah Sep 24, 2016
    I'm reading very useful information I didn't know about. So following every thing 100%.
    1. Christina (OC Team): So glad to hear you've found useful information. Good luck on your journey! - (Sep 24, 2016)
  18. Rossy Sep 27, 2016
    Hi, I am so happy to be here. I started taking brameston 2.5 on the 21st of August and stoped on the 19th of September. I ovulated on the 18th of September. My breasts are painful and heavy. Am I pregnant? Because I am expecting my next period on the 2nd of October. Wish me luck.
    1. Christina (OC Team): If you had sex in your fertile window, there's a possibility. Good luck!! - (Sep 27, 2016)
  19. Toyin Sep 28, 2016
    I will try this out but I need clarity on how to calculate my cycle. Is it after bleeding that my cycle days start counting?
    1. Christina (OC Team): Start counting on the first day of your cycle (first day of bleeding) until the day before your next cycle begins. - (Sep 29, 2016)
  20. Jasmin Sep 30, 2016
    I'm so happy I found this community. I'm learning so much info I never knew existed. Been charting my bbt now 7 days as well as taking prenatal vitamins. My cycle day has been 40 then 37 then this month 43days long. My cycle lengths vary so when would I ovulate? This is my first ttc using any scientific approach, imagine if I got pregnant, lol
    1. Christina (OC Team): Irregular cycles can make things more challenging. I'd suggest using OPKs. Charting BBT is a very accurate way to know when you ovulated, but OPKs will tell you before you are about to ovulate. Using both methods should cover you well. Good luck! - (Oct 01, 2016)
  21. LIL Oct 04, 2016
    Very helpful information. Can I start checking any time of the cycle or will I have to wait until the beginning of my cycle?
    1. Christina (OC Team): You can start now to get the hang of it, but in order to track a cycle, you should start at the beginning. - (Oct 05, 2016)
  22. Shonda Oct 05, 2016
    This is some very useful information about me getting pregnant, but I was pregnant last year in Nov and lost my baby. I only have my left tube left, but is it still a chance for me to get pregnant with one tube?
    1. Christina (OC Team): I'm so sorry for your loss. It is possible to get pregnant with one tube, but it becomes more important to track ovulation. Try using OPKs. Good luck! - (Oct 05, 2016)
    2. Shonda: What's the opk? - (Oct 06, 2016)
    3. Christina (OC Team): OPKs are Ovulation Prediction Kits that you can buy at most pharmacies. - (Oct 06, 2016)
  23. Ojay Oct 07, 2016
    Good morning my beautiful people. Still hoping and praying God answer my prayers this month.
    1. Christina (OC Team): Good luck!! - (Oct 09, 2016)
  24. Jideofor Oct 11, 2016
    Hi lovely people, from my calculation, I ovulated on the 27th of September and I had sex on the 26th of Sept, but I started menstruating today. Please I need an explanation.
    1. Christina (OC Team): Having sex in your fertile window doesn't guarantee pregnancy. It can take a healthy, fertile couple a few cycles of trying before they conceive. Good luck! - (Oct 12, 2016)
  25. Nayomy Oct 12, 2016
    My periods are supposed to come on the 22 of October and I utilized my fertile period really well. I don't want to jump into conclusions, but am really having strange feelings in the tummy. cramps, tickling feeling. Could it be something?
    1. Christina (OC Team): It sounds like a good possibility. Good luck!! - (Oct 12, 2016)
  26. Laura Oct 18, 2016
    Hi, I'm so grateful to be part of this community. I would like to use the BBT method to detect ovulation. But I'm kind of not sure if it is worth me doing as I was diagnosed of having pcos.
    1. Christina (OC Team): With irregular periods, BBT charting is most helpful as an indication that you have ovulated. I'd suggest also using another method, such as OPKs or tracking cervical mucus and position. The other method will tell you that ovulation is about to happen, and the BBT charting will tell you that it has completed. Together, you should have a good picture of your fertile window. - (Oct 18, 2016)
  27. Laura Oct 18, 2016
    Ok, many thanks. I'll try them.
  28. Oyedeji Oct 25, 2016
    Thanks a lot! Team OC!
  29. Beauty Oct 25, 2016
    Thanks to God. Help me. I want be pregnant immediately after my wedding in Dec. My period started on the 20th and ended the 25th. What do I do?
    1. Christina (OC Team): Start tracking your cycle to see when you ovulate. Have a look at this article - (Oct 26, 2016)
  30. Joy Oct 26, 2016
    I menstruated on the 23rd of Sept. I was on Clomid from day 2 to 5, and I did follicle tracking on day 12. There were two eggs on the 13th. Another follicle tracking was done and two eggs increased from 22mm and 25mm to 25 and 28mm on the 14th. One of the eggs ruptured and I had sex with my husband on day 14 and 16. On the 22nd of October, I felt very sick and the next thing was serious cramping and bleeding. I mean, my menses came again. My cycle is usually 29 days. I want to know where I got it all wrong. This pain and sudden flow is happening for the 2nd time. Please advise.
    1. Christina (OC Team): Hi, It sounds like it may be helpful for you to review this with your doctor. Good luck! - (Oct 26, 2016)
  31. Saa Oct 26, 2016
    I am grateful. Now I understand how important it is to have a thermometer. I will try and have one. I am grateful.

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