Whether you’re trying to get pregnant or avoid a pregnancy, an accurate basal body temperature can mean the difference between a positive or negative test. But will a simple $5 thermometer do the trick, or do you need to purchase one of the new smart models that cost over $200?
As fertility-tracking moms ourselves, we’ve tracked countless cycles and tested a wide range of BBT thermometers.
We’ve studied the differences between all the most popular BBT thermometers on today’s market to bring you the best basal thermometers for tracking ovulation. We chose these products based on their temperature accuracy, ease of use, tracking assistants such as apps or charts, and battery life.
If you want an inexpensive, easy-to-use, basic model or a more costly high-tech thermometer, we’ve got you covered. Check out our reviews of the top five thermometers for fertility tracking.
- Accurate readings to 0.01 degrees
- Soft beep
- All-inclusive, good value package
- Impressive app functionality
- Suits irregular cycles
- 1-year warranty
- Comfortable to wear
- Reliable results
- Tracks temperature & sleep quality
- Peak temperature alert
- Ovulation chart included
- Memory recall
Product Reviews
Here are 5 great basal thermometers for you to consider.
iProven Digital Basal Body Thermometer
Best Digital Basal Thermometer
This little thermometer from iProven is one of the best basal thermometers we’ve found.
To get the best results, you need a sensitive thermometer. This one is ultra-sensitive, giving you a precise reading to one hundredth of a degree. It’s not the fastest, as it measures your temperature over the course of a minute, but this enables it to get the most accurate reading.
One problem I’ve often found with digital thermometers is that the beep is too loud. However, the iProven model has a much softer beep than most thermometer beeps, alerting you that your reading is complete but ensuring you won’t disturb any co-sleepers.
One thing that stands out about the iProven thermometer is what’s included in the package. Besides the thermometer, you get a step-by-step guide and a temperature chart. I always prefer having a chart to write on as opposed to an app — it’s just easier for me.
The temperature chart will give you an overview of your cycle. This will help you identify your fertile window and assist your doctor in spotting any issues.
Pros
- Easy to use.
- Accurate readings to 0.01 degrees.
- Soft beep.
- Easy-to-read display.
- An all-inclusive, good-value package.
Cons
- No backlight for this particular model.
Our Ratings
Tempdrop Wearable Basal Body Temperature Monitoring Sensor
Best Wearable Basal Thermometer
This thermometer features a unique and ingenious armband design, allowing you to take your temperature without your family or co-workers knowing you are trying to get pregnant.
You wear the band with the sensor near your armpit overnight for continuous temperature tracking on your smartphone using a downloadable app (both iOS and Android). The application has impressive charting features, such BBT graph and a daily record of all your key measurements.
The measurements are fast and accurate and can be taken using two algorithms: a general learning algorithm and the patented Active Temperature-Noise Cancellation (ATNC) filtering algorithm. To simplify matters and reduce the possibility of human error, you only need to press the pink button once and it automatically starts recording.
Pros
- Highly accurate readings.
- Easy to use — wear the band and press the button once to record.
- Impressive app functionality.
- Suits irregular cycles.
- One-year warranty.
Cons
- The armband design could be more comfortable.
- Some useful data in the app can only be accessed by paying the monthly subscription fee.
Our Ratings
iFertracker Smart Fertility Tracker
Best Body Basal Thermometer
Wearing a basal thermometer might seem odd. But with this high-tech, sleek-looking model from iFertracker, you won’t notice.
Before you go to bed, place the sensor under your armpit. It will record your temperature throughout the night.
One feature that I’m sure you’ll love is its thorough readings. During the night, it gathers 20,000 temperature data points that you can view in the app in the morning.
After pairing the sensor with the app will automatically send all the data to your phone. However, since we sometimes tend to forget things, the sensor has a flash memory of 240 hours.
An additional feature that we can’t leave out is the sleep analyzer. The sensor will not only track your temperature but also how you sleep. How cool is that?
The sensor battery life needs some improvement. If you wear it every day like you’re supposed to, it will indicate “low battery” within a month. However, the CR2025 batteries are easy to replace and very affordable.
Pros
- Comfortable to wear.
- Reliable results.
- Tracks temperature and sleep quality.
Cons
- Short battery life.
- It can be difficult to connect it to your device.
Our Ratings
Easy@Home Smart Basal Thermometer
Best Smart Basal Thermometer
This smart basal thermometer from Easy@Home is well worth your time. The thermometer features a small, backlit screen that displays your temperature, then syncs to an app on your phone.
The basal thermometer has a high precision, measuring to the hundredth degree. Additionally, it will let you choose between Fahrenheit and Celsius.
This smart thermometer comes with the Premom app, which is compatible with both iOS and Android. When you create your account, it will give you unlimited cloud storage for all your recordings.
As you take your temperature in the morning, the results will seamlessly sync with your app. But remember to connect the thermometer to your phone before you take your temperature if you want your results to sync automatically.
The Premom app will analyze your data to give you an accurate fertility window. After a month or so, when it gets used to your regular cycles, the app will predict and even give you a warning before you ovulate.
However, the battery seems to run out rather quickly.
Pros
- Smart technology.
- Easy to use — syncs automatically.
- High precision.
- Includes quality cycle-tracking app.
- Reasonably priced.
Cons
- Short battery life.
Our Ratings
Mabis Basal Body Thermometer
Most Simplistic Design
The FDA-approved Mabis basal thermometer is created at an ISO-registered facility.
Mabis specially made this basal thermometer for women who are trying to conceive. Its memory recall feature will make it easier to keep track of your previous reading.
The battery is easy to change and lasts much longer in this basic model than in some other thermometers. And although it’s not backlit, we found the display easy to read, even in dim light.
Mabis also provides you with a temperature chart so you can easily track your cycles.
The only downsides we found with this thermometer are that it isn’t always as accurate as some others, and the sound indicator can be quite loud. But if you’re looking for a basic, inexpensive model to do the job, this one is a great choice.
Pros
- Long-lasting battery.
- Basal body temperature chart included.
- Peak temperature alert.
Cons
- Not as accurate as some other models.
- Loud indicator sound.
Our Ratings
What Is Basal Body Temperature (BBT)?
Your basal body temperature (BBT) is your lowest resting body temperature (1). To get a correct reading, taking your temperature has to be the first thing you do when you wake up.
As soon as you wake up and go to the bathroom, drink a glass of water, or perhaps enjoy a cuddle with your partner, your temperature changes. If you were to do just one of these activities before measuring your temp, it would be incorrect.
Before ovulation, your basal body temperature will be within the 97.0 to 97.7 F range. After ovulation, your BBT increases by a few tenths of a degree and will stay high until your next period. In other words, your cycle is divided into two parts: the first half is the cooler follicular phase, and the second half is the warmer luteal phase.
Separating the two is the temperature shift that marks that ovulation has occurred.
Before you ovulate, the high levels of estrogen in your body keep your BBT low. After ovulation, your body quickly begins to produce more progesterone. By looking for a sustained temperature rise for at least three days, you can confirm that you have ovulated and your body has moved on to the second phase of the cycle.
What Is a Basal Thermometer?
A basal thermometer looks and works very similarly to a conventional thermometer. However, they’re much more sensitive and can measure smaller changes in your BBT (2).
For example, a conventional thermometer may give you a reading of 98.2 degrees Fahrenheit. The basal thermometer would read 98.235 degrees Fahrenheit, giving you a more accurate reading.
Can I Use My Conventional Thermometer?
Some argue that to get a correct reading of your BBT, you only need a reading to the tenth degree. This is what you would get with any thermometer.
This might be enough for you if you’re not trying to conceive right away or are just curious.
If you want the best results, experts agree you’ll need a more sensitive thermometer. The temperature changes are small, and you might miss them with a less sensitive thermometer. If you have an irregular, short, or long period, predicting your ovulation can be extra challenging, so an accurate thermometer is a must (3).
Another reason to choose a basal thermometer is that many can store your readings. This way, you can wake up, take your temperature, then go back to sleep. You can write it down later in the day or sync it with an app.
How to Choose a Basal Thermometer
Basal thermometers come in all shapes and sizes. Some are high-tech and high-priced, while others look like standard thermometers.
Here are a few different types:
- Digital: These basal thermometers have a small display and an on/off button.
- Glass: Most doctors argue that glass mercury-free basal thermometers will give you the most accurate reading. These are fairly easy to use, and you won’t have to worry about battery life.
- Smart basal thermometers: These are the new competitors on the market. They often offer you a thermometer that pairs with a compatible app. These don’t look like conventional thermometers, and they might be expensive.
When buying a basal thermometer, you should consider your needs, the thermometer’s accuracy, and your budget. These can be more expensive than regular thermometers, but if you’re trying to conceive, you’ll need that accuracy.
We generally prefer digital basal body thermometers as they are highly accurate and easy to use and get quick readings. However, if you’re thinking about buying a digital thermometer, there are some things to consider beforehand:
Accuracy
This is a crucial feature. You’ll need a thermometer that will give you a reading to one hundredth of a degree. If you buy one that will only give you a tenth, it won’t be sufficient for charting because it can not pick up very slight elevations in temperature.
Batteries or Rechargeable
As you’ll be using the thermometer daily, the batteries can wear out quickly. Since there aren’t many rechargeable basal thermometers on the market, we’ve looked for energy-efficient models, so you won’t have to change the batteries constantly.
Good Quality
When comparing digital basal thermometers, we’ve found that many tend to stop working suddenly. Poor-quality basal thermometers might fail after a month or so, but this is less likely to happen if it’s of good quality. We’ve reviewed the feedback from hundreds of users to ensure the basal thermometers on our list are more likely to last.
Memory Feature
This is a make-or-break point for me. Sometimes, mornings get hectic, and you don’t have time to write down your BBT. Unless you have a perfect memory, a memory feature is essential. It will store at least one temperature reading so you can review it and log your details later in the day, not the moment you wake up when you’re still battling brain fog.
Why Track Your Basal Temperature?
Ovulation occurs when the ovary releases an egg. The site of rupture left behind on the ovary is called the corpus luteum, and it starts producing progesterone, which is responsible for the increase in temperature.
Once you see a sustained rise in body temperature, it’s highly likely the egg has been released and has already died. You then move into the luteal phase and can’t get pregnant for the rest of the cycle. Ultimately, conception will occur when intercourse happens in the few days before ovulation.
If you’re using this method as contraception, keep in mind that semen can live inside a woman’s body for up to five days (4). Combine this with the fact that the released egg can live for 24 to 48 hours, and you have about a 6-day fertile window before and including ovulation day in which you could become pregnant.
If you’re using this method to conceive, thermometers can confirm that ovulation has already occurred in a cycle, but only after the fact. Once you see a temperature increase, your chances of conception are very low since there is no egg.
Whether trying to conceive or trying to avoid a pregnancy, it is best to use basal body temperature thermometers alongside other symptoms, such as changes in cervical fluid, vaginal secretions, or cervical position.
How to Track Ovulation Using a Basal Thermometer
To successfully track your cycle, the best thing to do is print out an ovulation chart or download an app. Some basal thermometers come with a compatible app to help you out.
Follow these steps to track your basal body temperature (5):
- Pick a time: The first thing you’ll need to do is choose a time to measure your temperature. It must be in the morning when you first wake up — at the same time every day.
- Note your period: The best time to start is when your period begins. Note this as day one, and record your temperature.
- Continue through your cycle: Keep going, and note when your period starts and stops. Take your temperature with a basal body temperature every morning at the same time.
- Note your ovulation: You’ll likely see a pattern after a couple of months. Before ovulation, your BBT is lower — generally between 97.0 and 97.7 degrees Fahrenheit. When it increases to a range of 97.7 to 98.3 Fahrenheit and stays there for at least three days, you’ll know you’ve ovulated and are in the luteal phase. This pattern is called “biphasic” since it consists of two phases.
- Wait for your period: Roughly 14 to 16 days after ovulation, your temperature will drop, and you’ll get your period. If your temperature doesn’t go down for at least 18 days after ovulation, there’s a good chance you’re pregnant.
It’s only fair to mention that this method requires some time and patience on your part. But it’s cheap and easy and will give you a good sense of your cycle. It’s also a great idea to bring your notes to any doctor’s appointments since it can help to pinpoint any fertility problems.
Basal Thermometer FAQs
What is the Most Accurate Basal Body Thermometer?
How Do I Know If My BBT Thermometer is Accurate?
You’ll know your BBT thermometer is accurate if it consistently measures and displays readings to at least 1/10th of a degree.
You can test its accuracy by taking multiple readings at the same time under the same conditions to check for consistency or comparing it to a clinical thermometer.
When Should I Start Using a Basal Thermometer?
You should start using a basal thermometer when you’re planning to track your ovulation and fertility windows, typically several months before trying to conceive. This allows you to understand your cycle and pinpoint your most fertile days.
How Accurate is Basal Body Temperature for Birth Control?
Basal body temperature tracking can be quite accurate for birth control when done consistently and correctly, with about 76-88% effectiveness.
However, it requires strict daily monitoring and understanding of your cycle, and it’s often used in combination with other fertility awareness methods for better accuracy.
Can Room Temperature Affect BBT?
Room temperature can slightly affect BBT readings, especially if there’s a significant change in the room’s temperature.
But, as long as you’re sleeping in the same environment consistently, your BBT should reflect your body’s changes rather than the room’s temperature.
How Many Times a Day Should You Check Your BBT?
You should check your BBT once a day, typically first thing in the morning before getting out of bed, after at least 3-4 hours of uninterrupted sleep. Consistent timing gives the most accurate and comparable results.
