Daysy Review: My Honest Experience Using The Daysy Fertility Tracker

Natural Birth Control

I wanted to share my experience with the Daysy fertility monitor because I think my perspective could be helpful to other women. This isn’t sponsored (I saved up and purchased my own Daysy) and at the time I didn’t have this blog. But it was this journey that sparked my passion for fertility awareness and the knowledge of how our reproductive system actually works!..

What is the Daysy Fertility Tracker?

Daysy is a fertility tracker that uses the temperature method. It uses a unique algorithm that learns and tracks your cycle and displays your fertility in a color system [red = fertile, yellow = learning,green = infertile.] Daysy is all natural, free of side effects and no charting is necessary. Every morning when you wake up, you measure your temperature under your tongue. Enter if you have your menstruation then Daysy will evaluate your data and shows you if you are fertile or not.

My Daysy Review

This blog contains affiliate links; meaning if you click on a link and choose to make a purchase, we will receive a small comission, at no extra cost to you.

I’ve been using the Sympto-Thermal Method + the Daysy consistently since september 2017. (Update: I stopped using the Daysy in mid 2021 and now use TempDrop as my BBT thermometer. Please scroll to the bottom to read my full update)

For women who are concerned about the health, emotional, and environmental impacts of hormonal and other forms of birth control, the Daysy is a natural birth control method that claims to be 99.4% effective!

This has been my honest experience 💗

  • 20 months / cycles recorded
  • 0 pregnancies (not trying to conceive)
  • First 2 months of ‘learning’ my cycle
  • Green and red days on my 3rd cycle
  • Contacted support twice with questions about my cycle and their service was kind and impeccable



Where It All Began

I’m so grateful I stumbled upon this birth control option. It seemed to be an amazing solution to my hormonal-birth-control-depression / what-do-I-do-now crisis I was going through. 

Throwback to a journal entry I wrote about this time

“The sad bit was that now looking back, was that the depression was a slow decline that I almost didn’t even realise it was happening. I spoke to my partner about it one day – “I’ve never been this sad in my life – it must be the hormones” to which he replied “I’ve noticed it aswell but I didn’t want to say anything. You’re not my girlfriend right now. I am incredibly grateful for my wonderful life, and privilege of being Australian and living in this time in history which allows so many opportunities. But when I was crying and couldn’t get out of bed on holiday in Bali with no negative external circumstances to explain it, I knew things were bad.”

I know this is not an isolated occurrence with hormonal birth control. In fact, it’s probably more likely the norm than the exception. I made the decision that I could no longer sacrifice wellbeing in favour of pregnancy prevention – that would be my deal breaker.

What I Love About Daysy

No side-effects

Giving up hormonal birth control has been one of the greatest decisions of my life. It has benefited all areas of my life: my health, my wellbeing, and my relationship,  because it allows for greater honest communication. 

The easy color system

To know instantly if I’m fertile or not and which days will lead to pregnancy, instantly without charting is incredibly convenient and beautifully simple.

Green = infertile
Yellow = possibly fertile / daysy is learning about you
Red = fertile / possibly fertile

A non-hormonal birth control option

I get to experience my cycle with all my natural hormones
Much better than the withdrawal method, which in my opinion, is like a ticking time-bomb. It’s not an if, it’s a when.
It makes practicing natural birth control and fertility awareness EASY
As simple as the pill (take it everyday)
Daisy claims it’s 99.3% accurate with perfect use. 2022 Update: The study that this was based on has been pulled for selectively using data that made it look good — and undercounting possible unintended pregnancies. I have added these inks at the end of the review post. 

The design

It’s small and gorgeous

It’s quiet

The temperature taken alert is a vibration which doesn’t wake my partner / other bbt thermometers beep loudly.

It will tell you early if you’re pregnant

This is helpful as its very common for women don’t realise they’re pregnant until weeks in.

Customer support and advice when you need it

I’ve contacted support twice and their service was kind and impeccable.

Considerations: How To Decide If Daysy Is Right For You?

As with all fertility awareness methods, there are a couple of considerations worth mentioning upfront:

1. Daysy will not prevent the spread of STDs.

2. There will be a few days throughout each cycle where you’ll be fertile and therefore, you might be able to conceive! This means that if you’re not looking to get pregnant, you might like to use a barrier method of conception like condoms, or *get creative* without P in the V sex during this time.

In order to have an accurate reading, you’ll need to take your temperature after you wake up, first thing in the morning, before you do anything else.

This includes rolling around for a cuddle, getting up to go to the toilet, or scrolling through your phone.

I hardly miss taking my temperature (which I would have thought would happen quite often) but for me, I’ve found it quite automatic to remember first thing. When I realise I’m awake and no longer sleeping, I automatically reach for the daysy on my night stand and pop it in my mouth while I’m half asleep. There are times when I will purposefully skip taking my temperature; if I’ve been sick, really hung over or if I’m travelling and I haven’t had 3 consecutive hours of sleep. On the odd occasion I have completely forgotten or have mistakenly left it another room, woops, but it’s very rare.

You’re ‘meant’ to take your temperature at the same time every day, but this may not be necessary with Daysy.
Honestly, my wake up time varies from 6.30 – 10 most days and I’ve never had a problem with a weird reading or a pregnancy because of it. I think this is because the daysy is a highly sensitive and quality thermometer unlike a regular bbt thermometer. I find it more important to keep a similar temperature in my room throughout a cycle.

Syncing Daysy with the daysyview app requires wifi
I don’t understand this and it is a bit annoying since I travel frequently and sometimes I’m in remote location but it’s not usually a problem.

The chart on the daysyview app isn’t great
I think the apps chart is more for a visual representation of your cycle temperatures. This is understandable as the daysy device takes care of it all and you aren’t required to chart like a traditional method of fertility awareness. But the daysyview app’s chart isn’t detailed enough to be used to apply the sympto thermal rules. If you’re interested, you can always go more in depth by combining the daysy with a charting app like Kindara that has a beautiful interactive chart designed for the sympto thermal method and applying the rules.

The price is a one-off purchase for the device
There isn’t a monthly subscription (which I really like because a monthly cost definitely adds up!)

At the time the price was a lot of money for me. This didn’t mean I didn’t think it was worth the price, it was just that that was my financial situation at that time. So I saved up and purchased it. And it has been the best money I’ve ever spent.

It’s a pleasure to use and I get so so much value from it every-single-day because I’m no longer experiencing hormonal side effects and depression.

Giving up hormonal birth control and practising the Sympto Thermal Method of fertility awareness has been one of the greatest decisions of my life. It has benefited all areas of my life including my health and wellbeing. 

There have been debates on the daysy’s accuracy
Please keep reading for all the details and specific percentages on daysy’s accuracy.

2021 and Beyond Update:

I stopped using the Daysy in mid 2021. I found the daysy view app not detailed enough to confirm the symto-themeral method rules. And so, I was running two apps: daysy view and kindara for a long time, but it was making charting more difficult than they needed to be. For me, I got sick of the light system and I wanted to freely interpret my chart accoding the my method’s rules. 

As I was doing some more research on what to kind of themomitor to use instead, I found TempDrop and thought that would be perfect! However, across my research, I also learned something about Daysy that was concerning: The company claimed that the thermometer successfully predicted fertility in 99.4% of its customers. But the study that it was based on was pulled for selectively using data that made it look good — and undercounting possible unintended pregnancies.You can read more this at the buzzfeed article that broke the news here. You can read more about this at the reproductive health journal here.

Viginia of also had some concerns that I had whitness myself;
“In fact, when looking at it closer, I noticed that on many green days (= infertile) predicted by Daysy, I actually had a high-quality cervical mucus which is a sign of ovulation.Therefore, I could have gotten pregnant whilst following Daysy’s analysis. Doing my research, I found that I’m not the only person who experienced this.”

I noticed these discrepencies myself, and in my chart I added a ‘maybe fertile’ tick box that tracked when daysy’s green lights disagreed with my body’s fertility signs.

In the end, I had enough and just wanted to chart and interpret my fertility signs according to the symoto-thermal method without an algorithum confusing me.

I would like to note that a follow up study was conducted in 2021 ‘The Performance of a Fertility Tracking Device [Roemer 2021]’ A total of 0.6% of all displayed green (infertile) days by the Fertility Algorithm were identified as false positives. Therefore Vally Electronics (Daysy’s parent company) has stated an an overall accuracy of 99.4%. However, the indipendant study discusses that “skipping [missed BBT recording] seems to have a direct effect on fertility identification” and concludes “further research is needed to explore the efficacy of the device in a prospective study.”

2022 Update

I still use and love the sympto-thermal method, and I use this with the app ‘Read Your Body’ and the BBT themomitor TempDrop but I no longer use Daysy.

I hope that by sharing my daysy review and experience it was helpful in some way for you in making a choice whether the daysy might be right for you. You may find the simplicity of the Daysy is what you’re looking for — for those women Daysy would like to provide a special discount for our community:
For American & International Wonderful Within readers – Get $15 Off at
For European Wonderful Within readers – Get €10 off at

— Or this might propel an interest in learning to chart your cycle like the sympto thermal method. In either case, here’s to open communication, transparency and finding what works for you!


Other Posts You May Like:


In the interest of the community, we have chosen to allow discussion in accordance with our comment policy.
We value ideas, discussion and contribution. Our values are: empowerment, education and being supportive and uplifting to one another.


Submit a Comment

Your email address will not be published.

Wonderful Within is a blog designed to educate and empower women from within. We talk all things wonderful, including: menstrual cycles, periods, charting, fertility awareness and women’s health and wellness choices.


error: Copyright ⓒ Wonderful Within

Pin It on Pinterest