When using the Symptothermal Method of Fertility Awareness, a basal body temperature (BBT) thermometer is required. A BBT thermometer is a highly sensitive thermometer that measures accurately to two decimal places. This is important because the changes that you are looking to identify while charting can be as small as 0.2°C/0.4°F. Your basal body temperature is your lowest core body temperature achieved during rest and usually occurs around 4am in the morning. As most of us don’t want to be waking up at 4am every morning, we take our waking temperature a few hours later instead. Most women take their temperature orally, while others may opt to take their temperature vaginally.
When searching for a thermometer, you need to make sure that:
- You purchase a BBT thermometer that measures accurately to two decimal places
- You purchase a BBT thermometer and not a standard fever thermometer
(even though many standard fever thermometers will display two decimal places, they do not measure accurately enough to be used as a BBT thermometer)
You will find that most pharmacies stock BBT thermometers. If the pharmacist doesn’t know what you mean when you say you’re looking for a basal body temperature thermometer, try asking for an “ovulation thermometer”. Here on the Gold Coast my local pharmacy stocks the SurgiPack Ovulation Digital Thermometer 6335 or SurgiPack Ovulation Digital Thermometer 6332 for AU$20 and it’s as simple as walking into the pharmacy and grabbing one! You can also find these BBT thermometers on eBay Australia.
See below for a range of additional tried and true BBT thermometer options. You really don’t need anything fancy!
Keep in mind: It is difficult to keep up with Amazon links as products frequently go out of stock (especially more recently with the Coronavirus pandemic). Some of these thermometers only ship to specific countries and you may need to set up a drop-shipping account to have them sent outside of the United States to Australia or vice versa.
I personally use US Global Mail drop-shipping. To set up a drop-shipping account, visit https://inbox.usglobalmail.com/signup and use code JESSIE-L9ESJFFN.J0P for a complimentary month of service.
Please note that some of the links in this article are affiliate links meaning (at no additional cost to you) I may earn a commission if you click through and make a purchase. Your support helps to keep this site running and for that I am VERY GRATEFUL! For more information, please read the Advertising & Affiliates Policy here.
Australia: The Fertility2Family Digital Basal Thermometer
Fertility2Family is a great Australian company based in Tasmania. Their BBT thermometers were some of the only thermometers that remained in stock throughout the pandemic here in Australia. Keep in mind that it does not have an internal memory so cannot store more than a single temperature at a time. It also does not have a backlight so you’ll need to turn the light on in the morning to see your temperature. In saying this, I’m currently over 4 years into my charting journey with the Symptothermal Method and this has never bothered me; basic thermometers have always done well for me. Use code 5SDC2JYYI2 for 5% off: Purchase Now
United States: The iProven Digital Basal Thermometer
The iProven is a reliable, entry-level digital BBT Thermometer for an affordable price on Amazon. Keep in mind that it does not have an internal memory so cannot store more than a single temperature at a time. It also does not have a backlight so you’ll need to turn the light on in the morning to see your temperature.
United States: The Mabis Digital Basal Thermometer
Another reliable entry-level digital basal body temperature thermometer for those in the U.S. Keep in mind that it does not have an internal memory so cannot store more than a single temperature at a time. It also does not have a backlight so you’ll need to turn the light on in the morning to see your temperature.
United States: The Easy@Home Digital Basal Thermometer
The Easy@Home Digital Basal Thermometer is in a slightly higher price range. It has a large screen and a backlight so that you won’t need to squint or turn on a light early in the morning. This thermometer syncs to the Premom app, which is not recommended for Symptothermal Method charting; however, you can simply input your temperatures manually into a more suitable app (i.e. Read Your Body app) each day.
United States: The Femometer Vinca II
The Femometer Vinca II is a premium option and is very well suited for charting with the Symptothermal Method. It’s best to grab their Vinca II model which includes a screen for you to see your temperature (earlier models required you to sync the thermometer with their app to see your temperature each day). In addition to this, the Vinca II allows you to select from three different options for the duration of time it will assess your BBT:
1.) Fast Mode (30 seconds)
2.) Normal Mode (1-1.5 minutes)
3.) Mercury Mode (3 minutes)
Mercury Mode is especially beneficial as the formal rules of many Symptothermal Methods do call for at least a 3-minute assessment of your BBT each morning.
With the Femometer Vinca II you can also adjust the beep volume either up or down, plus you can store up to 300 temperatures.
The Daysy/Ladycomp/Babycomp Devices
These devices were previously marketed heavily on social media and YouTube, where paid influencers would explain that they were using the devices as contraception. Valley Electronics AG (the manufacturer), advertised the devices as 99.4% effective with perfect use for accurate prediction of the fertile window based on temperature alone. Unfortunately, the real effectiveness of the Daysy/Ladycomp/Babycomp devices remains unknown. Their most recent study was retracted from the scientific literature due to a number of fatal flaws that meant the final figures were unreliable. Read more about the retraction here, which was finalised after leading reproductive health epidemiologist Chelsea Polis published a peer-reviewed commentary outlining the flaws of the study. In addition, their previous study advertising a 99.3% perfect use effectiveness rate has also been criticised as being flawed.
As a personal anecdote – Valley Electronics AG (aka Daysy) does not take kindly to criticism and doesn’t have the best track record of transparency with their clients. In fact, during the entire year that it took for the journal Reproductive Health to retract the 2018 Koch paper, Daysy continued to advertise their device as 99.4% effective. In this case, their pursuit of profit was placed above their customers’ right to accurate and up-to-date information about the device they were purchasing. Also concerning is the continued support that this company receives from high-profile figures within the FABM and natural health world.
The verdict? Use at your own risk. Anecdotally, if I had to choose between Daysy and Natural Cycles I would choose Daysy as their algorithm does appear to be a lot safer (despite the lack of quality research to support it). You can read more about why I personally do not recommend these devices here: 5 Reasons I Don’t Use Daysy or Natural Cycles
Natural Cycles
Natural Cycles is an app that claims to predict your fertile window with 93% accuracy (with typical use) based on temperature alone. My personal opinion is that Natural Cycles is not conservative enough if you are seriously wanting to avoid a pregnancy. Anecdotally, not a week goes by that I don’t see women reporting unplanned pregnancies or being given “green” days during what would be identified as their fertile window with the Symptothermall Method. On top of this, the founder of the app (Elina Berglund) and one of the lead scientists behind the Natural Cycles’ studies (Kristina Gemzell) have both been quoted as saying this app is not a good option for those women who are seriously trying to avoid a pregnancy. You can read more about the reasons why I do not personally recommend Natural Cycles here: Natural Cycles’ FDA Approval: What’s The Big Deal?
Always remember that it’s best to work with an instructor to learn Fertility Awareness – an instructor will be able to guide you through all the nuances of accurately taking your temperature and the specific rules of confirming your temperature shift. They’ll also be able to help you develop a solid understanding of your cervical fluid, too. You can find an instructor here.
If you’re not financially ready to invest in an instructor, you can read about how to self-teach here.
Lastly, never swap thermometers (or the route you take your temperature) mid-cycle.
Do you have a favourite basal body temperature thermometer that has served you well? I would love to hear about it – please use the Contact Form at the bottom of this website to let me know!
