Menstrual cycles between 19 and 40 days
Daysy Fertility Tracker
Go natural and track your cycle confidently.
Portable. Accurate.
No subscription, no test strips, no hormones.
Got a period? You can use Daysy.
Daysy is a fertility tracker by Valley Electronics. It measures your basal body temperature (BBT) and identifies your fertile and non-fertile days. Designed and made in Germany for over 40 years.
Daysy works for:
You don’t have to live a certain type of lifestyle or avoid alcohol to use Daysy to track your fertility.
Fertility awareness for women ready to take matters into their own hands
Tired of feeling spaced out and on edge? Or jumping between methods without finding the one that works for you?
With Daysy, fertility tracking is simple: it measures your basal body temperature, detects your ovulation, and shows you with a traffic-light system whether you're fertile or not. Daysy determines your non-fertile days with a scientifically confirmed accuracy of 99.4%.1
Feel more in tune with your body and understand your cycle, day by day.
I’ve only had this device for two months and already it is MIND BLOWING how accurate it is.
I do manual FAM charting to cross reference and to be safe but each time it matches DAYSY’s predictions.
I absolutely love Daysy. She has been very easy to use and has taken away the fear and human error risk that comes with the fertility awareness method.
$300 is a hefty price tag, but 100% worth it.
Daysy is the light at the end of the tunnel for me.
I love this product mainly because it helps me a lot to know myself and understand a lot about cycles, PMS but also the emotional side! Highly recommend.
How does Daysy work?
Planning pregnancy? Postponing pregnancy?
Daysy’s got you through it all.
Can I use Daysy with irregular cycles or PCOS (now called PMOS)?
Yes, Daysy is built for irregular cycles.
Your fertility is serious business. You deserve only the best.
Find out why over 94% of Daysy users would buy Daysy again
So much more than a period tracking app or a simple ovulation calculator.
How does Daysy help you get pregnant?
Daysy detects your ovulation and shows your fertile window, the days with the highest chance of pregnancy. So you find your optimal window for conception, without ovulation tests.
When you know your ovulation and time intercourse accordingly, your chances of pregnancy increase. With timed intercourse, most couples conceive within six cycles, around 92% within a year 2.
Track your fertility daily with Daysy and learn if you're ovulating, if your cycles are regular, and which days are best for conception.
See how our cycle trackers stack up
| Lady-Comp | Daysy | Other period trackers |
|---|---|---|
| 99.4% accurate | 99.4% accurate | 93% accurate |
| No app needed | Works without an app | Needs both a thermometer and app |
| One-time purchase, no hidden costs (payment plans available!) | One-time purchase, no hidden costs (payment plans available!) | $9.99+ monthly subscription |
| Works offline | Bluetooth only on demand | Needs wifi to display fertility status |
| Reliable algorithm that works with irregular cycles | Reliable algorithm that works with irregular cycles | Algorithm uses AI to fill in the gaps |
| AAA batteries | Long battery life | Needs phone charger |
| Backlit display | Lights up with fertility status | No backlit display |
| Sensitive sensor that measures to the hundredth of a degree | Sensitive sensor that measures to the hundredth of a degree | Sensor only measures to the tenth of a degree |
| Detects hormonal deficiencies | - | - |
| Shows expected delivery date | - | - |
So many ways to save
Hear from more happy Daysy users
You don’t have to measure at the same time every day. Learn even more with our frequently asked questions about Daysy.
What is the best way to measure?
For optimal use of Daysy, we recommend that you should have slept sufficiently (at least one hour) before the measurement. It is important that you take your temperature immediately after waking up, before getting up and becoming active. Measure below your tongue, with your mouth closed, and keep the device steady while it is measuring. Video Tutorial
Do I have to measure at the same time every day?
No. You should have at least one hour of good quality sleep before the measurement. It is important that you take your temperature immediately after waking up, before getting up and becoming active. For optimal use of Daysy, try to get at least 3 or more hours of sleep before measuring. Less sleep can result in more temperature fluctuations causing Daysy to give more fertile or potentially fertile days.
How do I enter or edit menstruation?
You can confirm or remove menstruation at any time during the current day. Simply press the button to turn on your Daysy, and then press and hold the activation button until the violet light lights up without flashing and you hear a "beep." Confirm you are menstruating for each day of active bleeding and for a minimum of three consecutive days. You can also remove menstruation data for the same day by turning Daysy on and pressing and holding the activation button until the purple/blue light is no longer solidly lit and begins flashing again.
How long until Daysy knows my personal cycle?
The first 2-4 cycles of use are considered Daysy's learning phase. Over the course of her learning phase, Daysy will come to understand your cycle and begin narrowing down your fertile window. Daysy remains quite cautious and conservative during this time, which is why Daysy is accurate starting the very first day.
When can I start to rely on Daysy's results?
You can rely on Daysy's results starting the very first day of use. In the beginning, you will see more yellow and red days because Daysy is still learning your unique cycle. You will see more green days as Daysy comes to understand your cycle and can narrow down your fertile window. The more regularly you measure, the better.
My cycle is irregular. Can I still use the devices?
Yes. Irregular cycles are not a problem for Daysy/Lady-Comp. Even with irregular cycles, all Valley devices distinguish between non-fertile and fertile days with a very high accuracy. However, in case of extreme fluctuations between cycles it will give you more red and yellow lights and less green lights. Fluctuations of several days are usually not a problem. If you have questions about your unique cycle, please reach out to our team of experts.
Are there any costs associated with the DaysyDay app?
No! DaysyDay is free! There are no in-app purchases or upgrade fees.
Does illness reduce the reliability of the device?
In general, you should skip measurements during illness and while you are taking medication that can have an influence on your body temperature or cycle. If you have doubts, contact your doctor or our customer service team.
More:
Contact
Sources
1)
The performance of a fertility awareness based medical device to determine fertile and infertile days across the menstrual cycle.
The European Journal of Contraception & Reproductive Health Care.
26(2),
111–118
(2021).
DOI:
10.1080/13625187.2021.1871599.
Available at:
www.tandfonline.com
.
2)
Time to pregnancy: results of the German prospective study and impact on the management of infertility.
Human Reproduction.
18(9),
1959–1966
(2003).
DOI:
10.1093/humrep/deg366.
Available at:
academic.oup.com
.
3)
Daysy user survey (self-reported time to pregnancy), annual surveys 2022–2026.
Valley Electronics AG.
(2022).
Product details, warnings and safety information
Information about the device
Size:
13 x 4.8 x 2.2 cm
(HxWxD)
Weight:
38 g
Battery:
Permanently installed, rechargeable battery
EAN:
7629999054073
WEEE:
DE34917049
Warnings and safety information
Packaging
Daysy comes with a protective case, making it ideal for travel. The outer packaging of Daysy is made from recycled material.
Includes a quick guide, user manual, and micro USB cable.
Manufacturer
Valley Electronics AG
Wengistrasse 2, 8004 Zürich, Switzerland info@daysy.me +41 44577 6869
EU-Representative: M.I.S.S. GmbH Breite 2, 82418 Murnau a. Staffelsee, Germany info@eu.daysy.me