How To Track Your Cycle with Basal Body Temperature (BBT)
If you’re on a journey to balance your hormones, optimize fertility, or prepare for pregnancy, tracking Basal Body Temperature (BBT) is one of the most insightful tools you can use. BBT tracking is more than just a method to confirm ovulation—it also provides valuable clues about your overall hormonal health, including the health of your progesterone levels, which are critical for hormone balance, fertility and pregnancy.
In this article, we’ll explore what BBT is, how to track it accurately, how to use modern tools like the Tempdrop armband to simplify tracking, and how BBT patterns can reveal essential information about your progesterone levels and cycle health.
What is Basal Body Temperature (BBT)?
BBT is your lowest resting body temperature, measured first thing in the morning after at least three to four hours of sleep. Tracking BBT daily can help you identify patterns that confirm ovulation and reveal information about your progesterone levels and the health of your luteal phase (the time between ovulation and your next period).
Pre-Ovulation (Follicular Phase): BBT is typically lower, ranging between 97.0°F and 97.7°F.
Post-Ovulation (Luteal Phase): After ovulation, progesterone raises your temperature by about 0.5°F. This increase signals ovulation has occurred and the luteal phase has begun.
How to Confirm Ovulation with BBT
If you observe a sustained rise in your BBT of at least 0.5°F for three consecutive days, ovulation has occurred. Your ovulation day will be the first day of that rise.
Does BBT Predict Ovulation?
BBT does not predict ovulation; instead, it confirms that ovulation has already occurred.
However, tracking BBT consistently over time can reveal patterns in your cycle, including the typical timing of ovulation. These insights make it easier to estimate your next ovulation day, whether you’re planning to conceive or trying to avoid pregnancy.
Conception Tip: If you’re trying to conceive, focus on timing intercourse when you notice egg-white cervical mucus (a key sign of fertility) and in the days leading up to your predicted ovulation. This ensures sperm are present and ready to meet the egg when it’s released.
How to Assess Progesterone Levels with BBT
Progesterone increases your metabolic rate, which is why basal body temperature rises and why tracking BBT is a great way to assess progesterone levels.
Understanding Your Temperatures
As long as your temperatures remain elevated by half a degree after ovulation, you are in your luteal phase (the time between ovulation and your period) and know progesterone is being produced.
Healthy Luteal Phase and Adequate Progesterone:
In a healthy cycle, progesterone keeps BBT elevated for 12 to 16 days. If you observe this sustained rise, you’re producing healthy levels of progesterone for hormonal balance and to support pregnancy.Short Luteal Phase and Low Progesterone:
If your temperatures drop before 12 days, this indicates a short luteal phase and is reflective of low progesteone levels. Addressing this is essential if you’re aiming to balance your hormones or are trying to conceive. A classic, telltale sign of low progesterone is PMS.Elevated Temperatures Beyond 16 Days:
If BBT stays elevated beyond 16 days, you’re likely pregnant. However, other factors—such as illness, infection, or disrupted sleep—can also influence your temperatures. Conception Tip: BBT tracking can idicate pregnancy well before a pregnancy test!When Temperatures Drop:
When progesterone levels decline, your BBT will drop and menstruation will begin, marking the start of a new cycle.No Rise in Temperature:
If you don’t see a post-ovulation temperature rise, this is an anovulatory cycle, meaning no egg was released, and no progesterone was produced. You can’t get pregnant during an anovulatory cycle and progesterone levels will be low.
Key Takeaway:
For balanced hormones and optimal fertility, you want a sustained temperature rise of 12 to 16 days after ovulation. Another way to put this is you want your luteal phase to last 12 to 16 days. If you notice shorter or inconsistent luteal phases, this indicates low progesterone and it’s worth exploring further support through nutrition, lifestyle adjustments, or professional guidance.
If you have low progesterone or want to learn about the benefits of progesterone, beyond hormonal balance and pregnancy, read this article: Increasing Progesterone Naturally.
How to Track BBT with an Oral Thermometer
Traditionally, BBT is tracked with a thermometer, but consistency and timing are key to accuracy.
Step-by-Step Guide to Using a Basal Thermometer
Choose the Right Thermometer: Use a basal thermometer that measures to two decimal places (e.g., 97.65°F).
Take Your Temperature at the Same Time Daily: As soon as you wake up, before sitting up, eating, or talking.
Log Your Data: Record your readings in a fertility tracking app or on a chart to spot patterns over time.
Stay Consistent: Even small disruptions, like waking up at a different time or getting up to use the bathroom, can affect accuracy.
Pro Tip: It may take 2–3 cycles to notice clear patterns, so be patient and consistent.
This is an image of a BBT chart in the TempDrop app
Modern Tools That Simplify BBT Tracking
Tracking BBT with a traditional thermometer can feel like a hassle, especially if you have a busy lifestyle or struggle with waking up at the same time every day. Fortunately, modern wearable devices make it easier to collect accurate temperature data without disrupting your sleep or daily routine. Personally, I found tracking with an oral thermometer nearly impossible without interrupting my sleep, so switching to a wearable device has been a game changer for me. Here are a few wearable tools that simplify BBT tracking:
1. Tempdrop Armband
Tempdrop is an armband that you wear while you sleep, is a highly effective tool for tracking BBT while you sleep. Worn on your upper arm (during sleep only), it measures your body temperature continuously throughout the night, then syncs with the Tempdrop fertility app. The app help identify your fertile window, confirms ovulation, and provides valuable insights into your cycle. In addition to temperature tracking, the app lets you log information about your period, PMS symptoms, cervical mucus, and more. It also tracks your sleep, providing insight into your sleep hygiene and health. Note: Tempdrop doesn’t emit any EMF’s while you sleep.
2. Oura Ring + Natural Cycles
The Oura Ring is a wearable ring that tracks shifts in your body temperature, sleep patterns, heart rate, HRV, and more. When synced with the Natural Cycles fertility app, the Oura Ring provides insights into your cycle, including ovulation, your fertile days and your infertile days. You can also track your period symptoms, pregnancy symptoms and cervical mucus. Note: Oura Ring emits low EMF’s while you sleep.
3. Apple Watch + Natural Cycles
Natural Cycles now works with the Apple Watch. To use Natural Cycles with Apple Watch you need a model with temperature sensors, such as Apple Watch Series 8 or Apple Watch Ultra. Note: Apple Watch emits high EMF’s while you sleep.
My Preference:
I personally prefer TempDrop because the BBT tracking appears to be more accurate, it doesn’t emit EMF’s, and the cost is significantly lower in the long run. I have been using it for myself and with my clients since 2023 and have been very happy with it.
Use this link to get 15% off. This discount stacks on top TempDrop promotions!
A Quick Note on Complementary Fertility Tracking Methods
If you’re tracking your cycle for birth control purposes or trying to time conception, combining BBT with other tools—like cervical mucus and cervical positioning—can enhance accuracy.
Cervical Mucus: As ovulation approaches, cervical mucus becomes clearer, stretchier, and more abundant, resembling egg whites—indicating peak fertility. After ovulation, mucus typically dries up or becomes thicker, signaling the end of the fertile window.
Cervical Positioning: During your fertile window, the cervix rises, softens, and opens to allow sperm entry. After ovulation, it lowers, firms, and closes.
For natural birth control, combining these methods with BBT tracking help identify fertile and infertile days with more precision (but you need to be well educated on the Fertility Awareness Method before relying on this). For those timing conception, these methods help you maximize your chances by pinpointing the best days for intercourse.
If you’re not tracking for birth control or conception, BBT alone is often sufficient to understand your cycle and monitor ovulation patterns.
Disclaimer: Tracking BBT should not be used to prevent pregnancy on it’s own. If you’re interested in preventing pregnancy naturally, I recommend learning about the fertility awareness method, which utilizes BBT along with other metrics.
Recap: The Value of BBT Charting:
Confirms ovulation and the timing of it in your cycle
Tracks the length of your luteal phase
Indicates the quality of ovulation
Offers insight into progesterone levels
Reveals patterns that may reflect thyroid health
Helps predict your fertile window
Helps predict your infertile window
Addressing Cycle Challenges
Are you noticing a short luteal phase, temperatures that don’t stay elevated for 12-16 days, anovulatory cycles, or are experience PMS? These are clues that suggest your progesterone levels are low and that your body may need support to ensure hormonal balance, optimal fertility and overall health. If you’d like guidance in uncovering your root causes and want a personalized plan to support your unique need, let’s talk about working together!
