You're looking for an app to track your period, and you're wondering which one is really worth it. The right question is no longer just "which one best predicts my period", it's also "who has access to this data". Since the United States removed the constitutional right to abortion in 2022, and since a $59,5 million fine was imposed on one of the world's most downloaded apps for sharing menstrual data with Facebook and Google, the issue is no longer trivial.
We reviewed the most cited, most rated, and most discussed apps on this topic in 2026, to honestly tell you which one to choose based on what you're really looking for: accurate prediction, maximum privacy, or everyday simplicity.
💡 Before you download anything
Flo paid $59,5 million in September 2025 for sharing sensitive health data with advertising giants, despite its promises of confidentiality.
Clue remains the European benchmark. hosted in Germany, subject to GDPR, and ranked best free app by a study published in the journal Obstetrics & Gynecology.
Apple's Health app, already installed on your iPhone, offers end-to-end encrypted cycle tracking, free, and that nobody thinks to use.
No app can predict your ovulation with certainty. Calendar-based methods have around 85% reliability, compared to almost 98% for symptothermal methods.
Why the Question Is No Longer Just "Which Is the Most Accurate"
A period tracking app knows a lot about you: your cycle dates, your sex life, whether or not you've tried to get pregnant, and sometimes even a miscarriage. This data isn't protected by the same laws as your medical records at the doctor's office. In 2024, a study published in Computer Law & Security Review revealed that several fertility and period tracking apps were transmitting user data to third-party companies, sometimes without clearly informing users.
The most striking case remains that of Flo. The US Federal Trade Commission determined that the app shared sensitive health data with Facebook and Google despite its explicit confidentiality commitments, leading to a $59,5 million class-action settlement in September 2025. This is not a technical detail; it is exactly the kind of scenario that many users feared without being able to prove it.
💬 What you can check in 2 minutes
Before downloading, check if the app stores your data on your phone or on its servers, if it requires an account with your real email address, and if its privacy policy mentions sharing with "advertising partners." This information is usually found in the App Store's privacy policy, just before the download button.
The Ranking, According to What You're Really Looking For
We grouped the applications by user profile rather than by a generic ranking, because the "best" application depends entirely on what you expect from it.
Clue
The right balance
⭐⭐⭐⭐ 4,5/5
Over 1 million reviews on Google Play
This is the app I recommend first without hesitation. German, GDPR compliant, and ad-free even in its free version. A study by the journal Obstetrics & GynecologyThe app reviewer, which evaluated over a thousand such apps, ranked it the best free app based on 25 accuracy criteria. The interface is understated, lacking the usual garish pink of the industry, and users often describe it as an app they keep for years without switching.
The most common reason for feedback
"I have a real goldmine of information on my cycle, reliable forecasts without even paying."
"An intuitive app that finally helps me understand my cycle, even if it's irregular."
The symptom tracking is comprehensive and easy to complete daily, and the free version is quite complete. The only recurring complaint concerns the push notifications towards a premium subscription, which annoy some loyal users.
Free, with a Clue Plus option around €9,99/month for more in-depth analysis.
Apple Health app
Free and already on your phone
No separate note, natively integrated on iPhone
If you have an iPhone, you technically don't need anything else. The cycle tracking built into the Health app lets you record your period, cervical mucus, basal body temperature, and even receives data from your Apple Watch if you have one. The real game-changer is the end-to-end encryption on iCloud; Apple itself can't read your data.
The honest limit: The interface is less playful than Clue or Flo, and there's no educational content or community. It's a pure tracking tool, not a "lifestyle" app with articles to read.
Completely free, already installed by default on all recent iPhones.
Euki
Maximum confidentiality
⭐⭐⭐ 3,3/5
298 reviews, over 100,000 downloads on Google Play
Developed by a non-profit organization, Euki doesn't require an email address or account. All data remains solely on your phone, without any servers or tracking cookies. If you uninstall the app, everything disappears with it. It even offers a "distress" PIN that displays a fake screen if someone forces you to open it—a feature designed for truly sensitive situations.
The compromise: The interface is only available in English and Spanish; there's no French version yet, and the cycle analysis is more basic than Clue's. Its lower rating compared to industry giants also reflects a still-limited user community, not necessarily a quality issue. You gain in privacy, but lose in predictive accuracy.
Completely free, with no paid models.
Flo's
The most comprehensive one, to be used with your eyes open
⭐⭐⭐⭐ 4,7/5
Approximately 4,8 million reviews on Google Play
It's hard to ignore with its hundreds of millions of claimed users worldwide. The app covers a huge range of topics: cycle tracking, pregnancy monitoring, advice from over 100 healthcare professionals, and partner-led support. After the FTC scandal, Flo introduced an Anonymous Mode that disconnects your data from your identity—a real step forward, even if it came after the fact.
The most common reason for feedback
"I've been using Flo for years to track my periods, fertile days, and the regularity of my cycle."
The interface is praised for its clarity, but subscription reminders appear on almost every screen according to several long-time users, making the experience annoying even for those who have never had a problem with the features themselves.
Free, with a Premium subscription around €32,99/year. Activate Anonymous Mode upon installation if you choose this app.
Drip
For serious symptothermal methods
⭐⭐⭐⭐ 4,1/5
Approximately 400 reviews on Google Play, also available on iOS
If you truly want to pinpoint your ovulation rather than rely on statistical estimates, Drip goes beyond mainstream apps. It asks you to input your basal body temperature and cervical mucus to follow the symptothermal method, which can reach nearly 98% accuracy once mastered. Open source and developed in Germany, everything is stored locally on your phone, without requiring an account or server.
The most common reason for feedback
"No ads, clear interface, nothing is gendered, and the predictions remain accurate even with an irregular cycle."
Users particularly appreciate the complete absence of advertising and the fact that the interface is gender-neutral. However, several reviews point to a real bug with very long cycles exceeding 99 days, which can skew the displayed history if you have very irregular cycles or are using hormonal contraception.
Completely free, non-commercial project, with no advertising.
The Summary Chart for Choosing in 30 Seconds
| Application |
Ideal for |
Storage |
| Clue |
The right balance between accuracy and confidentiality |
European servers, GDPR |
| Health App |
iPhone owners who want something simple and free |
Local, end-to-end encrypted |
| Euki |
Absolute confidentiality, sensitive contexts |
Local only, no servers |
| Flo's |
Complete care, including pregnancy monitoring |
Servers, Anonymous Mode available |
| Drip |
Advanced symptothermal method, conception or natural contraception |
Local, open source |
What No App Can Truly Promise You
All these apps, even the most sophisticated ones, are still based on statistics derived from your previous cycles for the most part. This is called the calendar method, and its reliability for detecting ovulation is around 85%, which is okay for anticipating your period, but much less so for using it as contraception.
To accurately identify the day of your ovulation, the only method that approaches 98% reliability remains the symptothermal methodBy combining observations of your cervical mucus with your basal body temperature taken each morning. An app can help you record this data, but none can predict your ovulation for you without you making this observation yourself.
While Your Phone Calculates Your Period
No app, however accurate, can tell you what to wear on the day your period actually arrives. Our period panties offer up to 12 hours of protection, the equivalent of 3 to 4 tampons, for the days when the prediction is right, and especially for the days when it's wrong.
My advice if you only have to choose one
If you have an iPhone and just want to track your period without overthinking it, start with the pre-installed Health app; it's more than enough for most needs and doesn't require registration. If you want more in-depth symptom tracking and a real community to support you, Clue remains my default choice. Its European model provides reassurance regarding data privacy without sacrificing the accuracy of its predictions.
Whichever app you choose, give it 2 to 3 complete cycles before judging its accuracy. No algorithm can correctly identify a field it doesn't yet know on the first try.
Sources & References
- Federal Trade Commission (FTC). (2021, final regulations 2025). FTC v. Flo Health Inc., enforcement action regarding sharing of sensitive health data. FTC.gov
- Consumer Reports Digital Lab. (2022, updated). Period Tracker Apps and Privacy. ConsumerReports.org
- Apple Inc. Cycle tracking in the Health app, data encryption and privacy. Support.apple.com
- American College of Obstetricians and Gynecologists (ACOG). Menstrual cycle as a vital sign. ACOG.org
Note: App features, prices, ratings and privacy policies change regularly, always check the current terms on the store before downloading.
