Hormone-Free Fertility Tracker
Meet the Daysy Fertility Tracker
Daysy is a hormone-free fertility tracker that helps you understand your cycle through a daily basal body temperature measurement, supported by a 99.4% reliable smart internal algorithm.
The Product
Daysy Fertility Tracker
A precise basal-temperature sensor paired with a smart internal algorithm that learns your unique cycle. Measure under your tongue, and see at a glance whether today is fertile, non-fertile, confirm your menstruation days on Daysy.
Why Daysy
Why women choose Daysy
A more conscious, body-literate approach to your cycle — without hormones and without guesswork.
Natural Family Planning
Decide for yourself how, and whether, you want to prevent pregnancy.
Hormone-free
No synthetic hormones. Just your own data, gently interpreted.
Ovulation clarity
Recognize ovulation and expected menstruation with confidence.
Conscious cycle awareness
A calmer, more informed relationship with your body — every day.
App Ecosystem
DaysyDay App & Partner App
The free DaysyDay app turns each measurement into clear, personal cycle insight. The optional DaysyDay Partner App lets your partner stay informed — but only ever shows what you explicitly choose to share.
DaysyDay App
Your fertile window, expected period, statistics and journal — beautifully simple.
Partner App
Permission-based sharing. Your partner sees only what you decide, and nothing more. Privacy stays fully under your control.
Privacy
Your data, your control.
Your measurements are protected and stay with you. Outside parties never automatically have access. The DaysyDay Partner App is fully permission-based — sharing only what you explicitly choose, whenever you choose. Calm, considered, and entirely yours.
Protected by default
Encrypted, secure, private.
Permission-based sharing
You decide what is visible.
No automatic access
Outside parties stay outside.
Reliability
A precise sensor. A smart algorithm. A scientific foundation.
Daysy combines a high-precision basal-temperature sensor with an internal algorithm refined over years of cycle data and supported by published scientific study. The result: a daily indication you can trust.
Scientific study
Precise sensor
Smart algorithm
1:1 Support
Personal support for PMS, irregular cycles & hormone symptoms.
Educational, supportive 1:1 sessions designed around your cycle data. Built to help you understand patterns, ease symptoms, and feel more at home in your body. Not medical treatment — gentle, informed guidance.
Loved by women
Real stories, real cycles.
“After years on the pill, Daysy gave me back a sense of trust in my own body. Hormone-free finally felt possible.”
— Eva, 31“Three quiet seconds in the morning and I know where I am in my cycle. It’s become a calm little ritual.”
— Marie, 28“I wanted natural insight without an app reading my mood. Daysy is precise, private, and beautifully made.”
— Sophia, 35The Journal
Cycle education, hormones & wellbeing.
FAQ
Frequently Asked Questions
Clear answers to the questions women ask most before choosing the Daysy Fertility Tracker.
Women choose our medically certified hardware with built-in algorithms for superior accuracy and an integrated sensor that prevents measurement errors — even with irregular cycles. Daysy® is a cycle computer that shows your fertile and infertile days with 99.4% accuracy.
No yearly app subscriptions — Daysy pays for itself in 5 years. Full privacy protection, even when syncing to the Daysy app.
Begin today
Start with the Daysy Fertility Tracker
A hormone-free, beautifully made companion for understanding your cycle — and yourself.
