Daysy - your personal fertility tracker

Daysy gives you the choice!

Daysy is a fertility tracker that uses the fertility awareness method by learning and tracking your menstrual cycle. 

Daysy tells you when you are in your fertile window and when not. During your fertile window you can choose to plan a pregnancy, during your infertile phase you can not. It's your choice.

Daysy calculates your fertile window: Your fertility status will be displayed either as a red (you are fertile) or green (you are not fertile) light.

Daysy tells you when you are in your fertile window and when not. Daysy is not a contraception.


To the shop


As easy as 1, 2, 3...

Only 30-60 seconds per day!

Achieve a higher awareness of your body with Daysy: In just 3 steps and within 30-60 seconds per day!

  1. Every morning when you wake up, you measure your temperature under your tongue.
  2. Enter if you have your menstruation.
  3. Daysy evaluates your data for the next 24 hours and shows you if you are fertile or not.


Discover Daysy!


"Yes, I have recommended it several times!

Zoé, wedding planner

"I would definitely recommend it! I would tell them all the perks about it - no hormones, easy to use, chemical free. I'm trying to avoid getting pregnant right now and like having a natural option that I'm confident will work. "

Stephanie Danforth, Web Designer

"Daysy is so easy to use and What you get out of it is this wealth of information about your body. I now know the rhythms and the Health of my body, no guessing. I love Daysy and have told all my friends about it."

Mari, Teacher

"Daysy allows me to take control of my cycle without hormones or side effects. I can use Daysy and not have to worry about making errors the way I would with the calendar or mucus method alone. I can be confident that I am understanding my body well and being responsible with my future!"

Anonymous, high school math teacher:

USD 330.00

Add to Cart

You can count on Daysy!

Why is Daysy so reliable? The fact that Daysy can determine your fertile window is due to the extensive database. Based on 5 million menstrual cycles and an algorithm that draws on knowledge from more than 30 years of research, including clinical studies, Daysy can give you reliable information about your menstrual cycle.

  • Red = fertile
    On red days, you can plan for a baby.

  • Red flashing = predicted day of ovulation
  • Green = out of your fertile window
    You are not fertile on green days.
  • Yellow = learning phase/cycle variations
    On yellow days, Daysy becomes better acquainted with you. If pregnancy is out of the question for you right now, consider these days as red and use a barrier method of your choice or postpone PIV (penis-in-vagina) sex.

You can start with Daysy on any day of your cycle. Our customers appreciate the fact that measurement and fertility indicators can be seen independently of smartphone integration. Connecting to your smartphone is relevant for details and special features, e.g. if you want to display your menstrual cycle history or share it with your partner or doctor.

The algorithm of Daysy, which is also used by the well-known Lady-Comp fertility tracker of the sister company, has proven its safety for more than 3 decades. You will see how exciting it is to get to know your body better with Daysy!


  • Logo App Store
  • Logo Play Store

Keep track of everything with the Daysy app.

Simply connect your Daysy to the app DaysyView to see all your menstrual data at a glance.

Once you have connected Daysy to the app, the fertility tracker will automatically synchronize your data with DaysyView.

DaysyView shows you your individual menstrual cycle calendar, your temperature curve and a prognosis for the coming days and weeks.

Via the app, you can also share your cycle details with your partner or doctor.

Discover DaysyView!

  • Check out your daily fertility.
  • Check your weekly fertility status.
  • View your colorful monthly calendar.
  • Take notes.
  • Look at your predicted menstrual cycle curve.
  • Look at your temperature curve.
  • Check your menstrual cycle statistics.
  • Partner app – share your menstrual cycle data with your partner.
  • Enter when you had sexual intercourse.
  • Receive notifications when your menstrual cycle changes.
  • Contact our expert team if you need advice and support.
  • Receive free cycle analyses.

Medical basics related to the female cycle


Every woman is different,

but there are some basic physiological facts about the woman's menstrual cycle that you should know:

  • As a rule, every woman has only one ovulation per cycle.
  • If two or more instances of ovulation occur, they take place within 24 hours.
  • After ovulation, the ovum can be fertilized within 18 hours at the most.
  • Sperm is able to move and fertilize in a woman's body for a maximum of 5 days.

This means that pregnancy can occur on only 6 days, i.e. 5 days before ovulation and on the day of ovulation itself. Daysy calculates these 6 days, plus provides buffer days.


How exactly does the Daysy work?

Daysy uses a morning measurement of your basal body temperature to detect ovulation in your cycle. Just measure the temperature under your tongue in the morning and you will know whether you are fertile or not.

Depending on the current cycle phase, the fertility status indicator lights red or green.

In addition, Daysy records your menstrual cycle history and DaysyView shows you your past and present cycle data. It is hardly easier to become aware of your body.

Shopping Cart

Your cart is empty. Please add some products first.