BBT AI Interpreter
Enter your basal body temperature readings and AI will explain your chart in plain English.
Your temperatures are analyzed privately. No personal identifiers are stored or processed.
Example: 97.2, 97.1, 97.3, 97.4, 97.2, 97.8, 98.1, 98.2, 98.0, 98.3
Important: The information provided on this website, including all tools, calculators, AI analysis, and articles, is for educational and informational purposes only. It is not intended to be and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
What Is Basal Body Temperature and Why Does It Matter?
Basal body temperature (BBT) is your lowest resting temperature, measured first thing in the morning before you get out of bed. It typically sits between 36.1C and 36.4C before ovulation, then rises by 0.2-0.5C after the egg is released and stays elevated for the rest of your cycle.
This shift happens because progesterone — the hormone that surges after ovulation — raises your body temperature. By tracking BBT daily and plotting it on a chart, you can confirm when ovulation occurred and identify patterns across cycles. Unlike ovulation predictor kits, BBT tells you ovulation has happened rather than predicting it.
How to Take Basal Body Temperature Correctly
Accurate BBT tracking requires consistency. Small changes in routine can shift your reading by enough to obscure the pattern.
- Take your temperature at the same time every morning — ideally within 30 minutes of your usual wake time
- Measure before getting up, talking, eating, or drinking anything
- Use a dedicated BBT thermometer that reads to two decimal places
- Take it orally, vaginally, or rectally — but use the same method every day
- Get at least three consecutive hours of sleep before measuring
- Note anything that could affect your reading — illness, alcohol, late night, travel across time zones
Reading Your BBT Chart
A healthy BBT chart shows two distinct temperature phases — this is called a biphasic pattern. The first phase (follicular) runs from your period to ovulation, with lower temperatures. The second phase (luteal) follows ovulation with consistently higher temperatures.
BBT ovulation chart signs to look for: A sustained rise of at least 0.2C above your pre-ovulation baseline, lasting at least three days, confirms ovulation occurred. The day before the rise is typically your most fertile day.
Implantation dip on BBT chart: Some women see a one-day temperature drop around 7-10 days past ovulation. This is called an implantation dip. It is not a reliable sign of pregnancy on its own — many women see it without being pregnant, and many pregnant women never see it.
Pregnant BBT chart vs not pregnant: If your temperature stays elevated beyond day 16 of your luteal phase, this is a strong early sign of pregnancy. A chart that stays high for 18 or more days post-ovulation is considered a reliable pregnancy indicator.
Frequently Asked Questions
What does a BBT chart look like when pregnant?
A pregnant BBT chart stays elevated through what would normally be your luteal phase drop. If your temperature remains high for 18 or more days past ovulation without a period arriving, pregnancy is very likely. Some charts show a triphasic pattern — a third temperature level even higher than the post-ovulation rise — around the time of implantation.
When does BBT drop if not pregnant?
If you are not pregnant, your BBT will drop back toward your pre-ovulation baseline roughly 10-14 days after ovulation, just before or as your period starts. This drop happens because progesterone falls when the corpus luteum breaks down. A temperature drop after a sustained rise is a reliable sign your period is coming.
What is an implantation dip on a BBT chart?
An implantation dip is a single-day drop in BBT occurring 7-10 days past ovulation, followed by temperatures rising back to luteal phase levels. Research suggests it may correlate with implantation in some cycles, but it is not a reliable pregnancy indicator. Many cycles show a dip without pregnancy, and many pregnancies show no dip at all.
What is a triphasic BBT chart?
A triphasic chart shows three distinct temperature levels — the pre-ovulation baseline, the post-ovulation rise, and a third even higher level occurring later in the luteal phase. Triphasic charts are associated with early pregnancy but are not conclusive. A pregnancy test remains the only way to confirm.
What does a cervical mucus chart show?
Cervical mucus changes throughout your cycle in predictable ways. After your period it is typically dry or sticky, becoming creamy and then wet and egg-white-like as ovulation approaches. Tracking mucus alongside BBT gives a more complete picture of your fertility — mucus predicts ovulation while BBT confirms it happened.
How many cycles do I need to track BBT before it is useful?
Most women start to see reliable patterns after 2-3 full cycles of daily tracking. The first cycle is often about establishing your personal baseline. By the third cycle you should have enough data to predict ovulation timing and identify whether your luteal phase is long enough for implantation.
BBT charting is an educational tool and not a substitute for medical advice. If your charts consistently show no biphasic pattern or your luteal phase is shorter than 10 days, speak to your healthcare provider.