Do you want to start using symptothermal method but don't know which basal thermometer to choose? A classic thermometer is not enough, You need a two-decimal-place model (which displays 36,78°C and not just 36,8°C) to detect the tiny temperature variations that confirm ovulation (about 0,2 to 0,5°C).
Choosing between a classic digital thermometer, a connected model with an app, or a vaginal sensor can seem overwhelming. We've tested and compared the best symptothermal thermometers on the market to help you find the one that fits your budget, lifestyle, and needs. Spoiler: you don't need to spend €150 on a good thermometer; there are excellent models starting at €15.
⚡ Our selection
Symptothermal Method: Quick Reminder
Before choosing your thermometer, here's a quick reminder of what symptothermal method is. It's an ultra-effective natural contraceptive method (98,2% according to the WHO) that combines the observation of two fertility indicators: your basal temperature upon waking and the appearance of your cervical mucus.
Your body temperature increases by 0,2 to 0,5°C after ovulation due to progesterone. This increase confirms that ovulation has occurred. By cross-referencing this information with your cervical mucus, you can accurately determine your fertile days (when you should use protection) and your infertile days (when you are unlikely to get pregnant).
💡 Learn & Master Symptothermal Method From A to Z →
Comparison Table of the 5 Best Thermometers
The Criteria for a Good Basal Thermometer
Not all thermometers are created equal when it comes to symptothermal method. Here are the essential criteria to check before purchasing.
The 6 essential criteria
1. Precision to two decimal places (mandatory)
The thermometer should read 36,78°C, not 36,8°C. The temperature variation after ovulation is only 0,2 to 0,5°C. Without two decimal places, it is impossible to reliably detect it.
2. Measurement time (important)
Choose a thermometer with a slow measurement time (60 seconds minimum, ideally 2-3 minutes). Thermometers that are too fast (30 seconds) give a less reliable approximation of your true basal temperature.
3. Soft and comfortable tip
You'll be using it every morning for years. A stiff tip can be uncomfortable, especially for vaginal or rectal measurements (more accurate than oral measurements).
4. Temperature memory
At a minimum, it should remember the last temperature. Ideally, it should keep the last 30 measurements to avoid transcription errors if you forget to record your temperature immediately.
5. Backlit screen (bonus)
Handy for reading the temperature in the dark without having to turn on the light and risk waking you up completely. Not essential but very comfortable.
6. Soft beep
A shrill beep that jolts you awake isn't ideal. Make sure the beep is soft or adjustable.
🚫 What does NOT work for symptothermal method
- Conventional medical thermometers (one decimal place)
- Forehead or ear thermometers (not accurate enough)
- Room or kitchen thermometers (obviously)
- Apps that "predict" ovulation without actually taking a temperature (Flo, Clue free version, etc.)
The 5 Best Thermometers in Detail
Cyclotest Lady
The best value for money
The Cyclotest Lady has been a staple of symptothermal method in France for years. Simple, reliable, and made in Germany by a renowned brand in natural contraception, it remains the number one choice for getting started without breaking the bank. With its flexible tip and fast measurement, it does exactly what it's supposed to: accurately measure your basal temperature.
✅ Highlights
- Very affordable, perfect for beginners
- Fast: Measures in 30 seconds to 1 minute
- Flexible and comfortable tip
- Made in Germany (recognized Cyclotest brand)
- Memorizes the last temperature
- Comes with a storage case and cycle tracking sheets
❌ Weak points
- No backlit screen
- You must record the temperature manually in an app or on paper
👤 For whom? Symptothermal method beginners who want a reliable thermometer without breaking the bank. Those who don't need Bluetooth connectivity.
Femometer Vinca
The best affordable connected
With its lipstick-shaped design, the Femometer Vinca is unlike any other basal thermometer. Beyond its aesthetics, it offers automatic Bluetooth connectivity and a comprehensive free app. For those who want to go connected without spending €100, this is the best compromise on the market.
✅ Highlights
- Elegant lipstick-shaped design
- Automatic Bluetooth connection with the Femometer app (iOS and Android)
- Storage of 300 temperatures in internal memory
- Backlit screen for reading in the dark
- Automatically turns on/off when the cap is removed/replaced
- Free app (but some advanced features are chargeable)
❌ Weak points
- The Femometer app collects data for Chinese "big data" (Bongmi servers)
- Some users report sometimes inaccurate measurements.
👤 For whom? Those who want a smart thermometer without breaking the bank. Perfect if you love designer objects.
Cyclotest mySense
The most complete
The Cyclotest mySense is the premium symptothermal thermometer. A certified medical device, manufactured in Germany to rigorous quality standards, it stands out above all for its free lifetime app (no hidden subscriptions, ever). It's the smart investment for those who want a reliable, long-term solution with the best quality-ethics ratio on the market.
✅ Highlights
- Free app for life, no subscription or in-app purchases
- Class IIa certified medical device (TÜV certification)
- Made in Germany, impeccable quality
- Algorithm based on the NFP (Natural Family Planning) method
- Data stored on a secure server in Europe (GDPR)
- Memorizes 30 temperatures
- Backlit display
- Compatible with iOS, Android and Huawei
❌ Weak points
- High price (but pays off in the long run since the app is free for life)
👤 For whom? Those who want the best thermometer on the market with a reliable, ethical, and subscription-free app. A long-term investment.
Easy @ Home
The low price is effective
The Easy@Home is the entry-level thermometer that proves you can get good equipment without spending a lot. For less than €15, you get a backlit display, decent accuracy, and compatibility with the Premom app. It's ideal for testing symptothermal method without any financial commitment, although opinions sometimes differ on the reliability of the measurements.
✅ Highlights
- Very affordable (less than €15)
- Blue backlit LCD display (useful in the dark)
- Slow measurement (2 minutes) = more reliable than a fast thermometer
- Soft beep at start, two beeps at end
- 30 measurements in memory
- Compatible with the Premom app (free, iOS and Android)
❌ Weak points
- Some reviews mention sometimes inconsistent measures
- No Bluetooth connection (manual entry in the app)
👤 For whom? Very tight budget. Those who want to try symptothermal method without investing a lot at the beginning.
Trackle
For complex situations
The Trackle is a game changer. It's a vaginal sensor that you insert at night and stays in place all night to continuously measure your temperature. No need to remember to take your temperature when you wake up; the Trackle does the work while you sleep. A premium solution for situations where traditional symptothermal method therapy becomes too restrictive: irregular cycles, nighttime schedules, young children who disrupt sleep, frequent travel.
✅ Highlights
- Continuous measurement throughout the night (every minute during sleep)
- Ideal for irregular cycles, night shifts, young children, jet lag
- No need to remember to take your temperature every morning
- Only 4 hours of sleep minimum (vs 5 hours for others)
- Algorithm based on the Sensiplan method (very rigorous)
- Certified medical device (TÜV, class IIa)
- Free app, secure data in Germany
❌ Weak points
- High price
- Limited lifespan (approximately 2-3 years)
- Requires being comfortable with your body (vaginal insertion every evening)
👤 For whom? Complex situations where traditional temperature taking is difficult (night work, frequent travel, very irregular cycles, baby waking you up at night).
Protection During Your Period
Whether you practice symptothermal method or not, our Period Panties offer you protection and comfort during your period.
How to Take Your Basal Temperature Correctly
Having the right thermometer isn't enough. You also need to know how to use it correctly to obtain reliable and usable temperatures. Here's a step-by-step guide.
The temperature taking protocol
Step 1: Upon waking, BEFORE any activity
Take your temperature as soon as you open your eyes, before getting up, talking, drinking, or eating. Even sitting up in bed can raise your temperature slightly. Ideally, keep your thermometer on your nightstand.
Step 2: Choose a measurement location
Three options: mouth (under the tongue), vagina, or rectum. The vagina and rectum provide more stable and accurate measurements than the mouth. Once you choose, stick with it.
Step 3: Remain still during the measurement
Do not move, keep your mouth closed (for oral measurement). Wait for the beep indicating the end of the measurement.
Step 4: Immediately note the temperature
Either in your app (automatically if you have a connected thermometer), or on your paper chart. If you have a thermometer with memory, you can do this during the day, but be careful not to forget.
Step 5: Note any disruptions
Alcohol the night before, late bedtime, stress, illness, medication, disrupted sleep: all of these can distort your temperature. Note this on your graph so you don't misinterpret a rise or fall.
🚫 The 7 golden rules for a reliable temperature
- At a fixed time: Take it every day at the same time (± 30 min maximum tolerance)
- After 5 hours of sleep minimum: Your body must be at rest for at least 5 consecutive hours
- Same thermometer always: Do not change thermometers during the cycle
- Same location always: If you start at the mouth, stay at the mouth
- Before any activity: No getting up, no toilet, no movement
- Thermometer near the bed: So you don't have to search or move
- From day 1 of the cycle: Start on the first day of your period
Vaginal Thermometer: Benefits and Instructions for Use
Vaginal measurement is more accurate than oral measurement because vaginal temperature is less influenced by external factors (mouth breathing, ambient air). This is why many practitioners of symptothermal method prefer this method.
How to do : Insert the thermometer tip 2-3 cm into the vagina, like a tampon. Remain still until the beep sounds. Remove and read the temperature. Clean the thermometer with warm, soapy water or a disinfectant wipe.
Thermometers suitable for vaginal measurement: All the thermometers in our selection (except Trackle, which stays in place all night). Choose a model with a thin, flexible tip for greater comfort.
How to Track and Interpret Your Curve
Taking your temperature is great, but you still need to know what to do with it. Your temperature chart should help you visualize your cycle and identify when you're ovulating.
What a normal curve looks like
A typical symptothermal curve is broken down into two phases:
Follicular phase (low temperatures)
In the first part of your cycle, before ovulation, your temperature is low and relatively stable (usually between 36,1 and 36,5°C). It may fluctuate slightly from day to day.
Temperature rise (ovulation)
After ovulation, your temperature rises sharply by 0,2 to 0,5°C over 1 to 3 days. This rise confirms that ovulation has occurred.
Luteal phase (high temperatures)
Your temperature remains high (high plateau) for 10 to 16 days, until your period arrives. If you are pregnant, it remains high beyond 18 days.
How to identify the end of your fertile window: You become infertile again on the evening of the 3rd consecutive day of high temperature AFTER your cervical mucus peak. This is the rule of double monitoring in symptothermal method: both indicators (temperature AND mucus) must confirm the end of fertility.
Connected Thermometer VS Classic Thermometer
Should you invest in a smart thermometer, or will a traditional model suffice? It all depends on your needs and budget.
Our recommendation: Start with a standard thermometer like the Cyclotest Lady for 3-6 cycles to fully understand the method. Once you've mastered interpreting your curves, you can switch to a connected thermometer if you find manual entry too cumbersome.
Frequently Asked Questions
Which Thermometer to Choose?
If you are new to symptothermal method, start with the Cyclotest Lady (15-20€). This is the best value for money, it is reliable and allows you to learn the method without investing a fortune. After 3-6 cycles, if you find manual entry too restrictive, move on to Cyclotest mySense (€130) with its free app for life.
If your budget is very tight, theEasy @ Home (10-15€) does the job. If you have irregular cycles, work nights or travel a lot, invest in the Trackle (160€) which measures your temperature all night long.
In any case, avoid conventional medical thermometers (one decimal place) and apps that predict ovulation without actual observation. And above all: a good thermometer isn't everything; you also need to learn the method with serious training.
Warning : This article is for informational purposes only. Symptothermal method requires rigorous training to be used as a contraceptive. Consult a certified instructor for proper training.
