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Thermometer Guide

One of the essential tools to use the Symptothermal Method and other Fertility Awareness Based Methods is a basal thermometer, which is used to measure one of the main indicators that we observe: the basal temperature.

Tempdrop basal temperature

¿What is basal body temperature (BBT)?

Symptothermal Method | Havva FEM

The BBT It is the body temperature we have when we are completely at rest; just before waking up. Ovulation can cause a slight increase/rise in basal temperature (this is why we keep record of it).

There is a big variation in the price of basal thermometers, depending on the way they measure, the practicality, the technology they use, etc.

Although it may sound VERY tempting to buy a device that does everything for you from the beginning, my recommendation is that first you understand and internalize the rules of the Symptothermal Method and then seek to facilitate its use.

In this way, you learn to observe and interpret the signals that your body gives as well as to trust yourself and what you observe. This will help you a lot when making decisions in case you find faults in the measurement of any thermometer.

It's important to remember that electronic devices can fail or malfunction. It is rare, but you have to be aware of it.


To begin this wonderful journey of gettign to know your body and cycles, I recommend that you consider the following information before buying a thermometer, so you can choose the best one that fits YOUR needs:

  • If it has memory capacity. Some of them are capable of keeping track of late measurements in case you forget to chart one day.

  • If it has an app where temperatures are saved automatically or if you must record and save them manually.

  • Measurement accuracy must be 1/100 degrees, which means it has two decimal digits.

Looking for the right thermometer might be overwhelming at the beginning. That’s why I created this guide. I did the research, so you don’t have to!

Contact me if you need personalized help finding the ideal basal thermometer.


  • Technology can be a game changer in simplifying measurements and be a time + effort saver, but electronic devices that are in direct contact with the skin can be disruptors of our cycles because of bluetooth frequencies. If you are looking to live as “clean” as possible, you can use a basic Digital Basal Thermometer. Sometimes less is more.

  • A lot of the thermometers’ apps predict your ovulation window and your period. This can be helpful for someone who has absolutely no idea of how their cycle works, but if you’re learning a Fertility Awareness Based Method (FABM)/Natural Family Planning Method (NFP), I will always recommend to ignore those predictions and stick to the rules that your instructor taught you.

  • The beep volume is relative. If you take your temperature vaginally or rectally, you might want to buy a loud beep thermometer. If you take it orally and you don’t wanna wake your partner/baby up, you might want to consider a low volume beep one.

  • Some thermometers are FSA/HSA eligible. This is convenient when you want to buy a more expensive thermometer.

*Havva FEM might receive a small affiliate percentage of the sales of some of the products listed above.*

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