In plain terms: Flo and Clue are both capable mainstream trackers, and the honest answer depends on what you need with PMOS (formerly PCOS). Full disclosure: we make a different app, Vera. This comparison uses only what Flo and Clue publish about themselves, as of July 4, 2026.
If you’ve narrowed your choice to Flo and Clue, you’re weighing two of the biggest names in cycle tracking. Both approach PMOS mostly through general features and editorial content; the condition was only renamed from PCOS in May 2026, and app copy hasn’t caught up yet (Endocrine Society, 2026). Here’s where each one fits, side by side and without drama.
The short answer
Choose Flo for breadth: life-stage modes from pregnancy through perimenopause, a very large user base, and a large medically-reviewed content library. Choose Clue for detailed symptom logging, wearable integrations, and an EU data posture under GDPR. Neither names a PCOS-specific feature on its US App Store listing, as of July 4, 2026.
That’s the whole verdict in one paragraph. The rest of this post shows the evidence behind it, so you can weigh the parts that matter to you. If you’d like the wider field, our 2026 roundup of cycle tracking apps for PMOS compares six apps.
How they handle cycles that vary in length
With PMOS, cycles are often longer than the textbook picture, and that’s worth naming before we compare features. The NICHD puts a typical adult range at 21–35 days, and a large digital-health study of more than 600,000 cycles found an average near 29.3 days (NICHD; npj Digital Medicine, 2019). Longer and variable cycles can simply be normal for you.
Both apps are built around predictions, in their own words. Flo’s App Store listing describes ovulation and fertile-window predictions (Flo). Clue’s listing describes “personalized ovulation and fertile window predictions, based on a clinically-validated algorithm” (Clue).
Treat those as each company’s own feature descriptions, not as something your body owes an app. If a projected window and your actual cycle don’t line up, that reflects how the app models cycles, nothing more. You can use either app for plain, useful logging and give the projected windows as much or as little weight as you like.
Logging and the whole-body picture
PMOS reaches well beyond the ovaries: hormones, metabolism, skin, energy, sleep, and mood all belong in the whole-body picture. So logging breadth is a fair way to compare these two.
Flo logs 70+ symptoms and moods, basal body temperature, a week-by-week pregnancy mode, and perimenopause tracking with a “Perimenopause Score.” Its Premium symptom checker “provides educational information on PCOS, endometriosis, and fibroids symptoms,” per its listing; it’s part of the paid subscription.
Clue tracks 200+ symptoms and experiences, across period, trying-to-conceive, pregnancy, and perimenopause modes. It integrates with Apple Watch, Oura, WHOOP, Withings, and Fitbit, and offers a library of 400+ articles, per its App Store listing.
Worth repeating: neither app names a PCOS-specific feature on its US App Store listing, as of July 4, 2026. Flo’s paid symptom checker is educational content, and Clue’s PCOS material lives in its editorial library. If you log daily and love detail, Clue’s 200+ trackables give you more room. If you want one app to carry you through several life stages, Flo’s modes go further.
Price
Flo is free with in-app purchases from $1.99 to $59.99, as listed on the App Store. Clue’s paid tier, Clue Plus, costs $9.99 per month or $39.99 per year. Both prices are as of July 4, 2026, and both apps let you start logging on the free tier before you decide.
Privacy, briefly
Flo stores your data in the cloud, with an account by default, and its App Privacy label lists purchases, location, identifiers, and usage data under “Data Used to Track You.” Its notable feature is Anonymous Mode, which lets you use the app without your name, email, or technical identifiers associated with your health data. Flo has open-sourced it, built on Oblivious HTTP (Flo newsroom).
Clue requires an account and stores data on AWS servers in the European Union, under GDPR. Its privacy policy, dated May 20, 2026, states that “the sensitive health data you track in the Clue app is never shared with or sold to advertisers.” De-identified research sharing happens only if you switch on a consent toggle.
That’s the two-paragraph version. For labels, deletion paths, and the fine print, read our PMOS privacy guide to period apps.
So which one, for PMOS?
Choose Flo if you want one app across many life stages, a large medically-reviewed content library, and educational PCOS material inside the app through its paid symptom checker. It also fits if Anonymous Mode matters to you among cloud-based trackers.
Choose Clue if you log in detail every day and want 200+ trackables, wearable data from Apple Watch, Oura, WHOOP, Withings, or Fitbit, and a clear EU data posture with a plain never-sold sentence.
There’s no winner to crown here. Both are capable apps from established companies, and both publish their features and policies openly. The better tracker for your PMOS is the one you’ll actually open on an ordinary Tuesday, so consider trying each free tier for a cycle or two.
One transparent note, since we make a competing app. If you’re on iPhone and want PMOS-specific, on-device tracking that treats long and variable cycles as normal for you, our app Vera is a third option. Daily logging is free with no account, everything stays encrypted on your phone, and Vera never predicts: Day 47 is simply Day 47. You’ll find it compared honestly alongside Flo and Clue in our full roundup.
Frequently asked questions
Is Flo or Clue better for PCOS?
Neither names a PCOS-specific feature on its US App Store listing, as of July 4, 2026. Flo’s Premium symptom checker “provides educational information on PCOS, endometriosis, and fibroids symptoms” as part of the paid subscription. In practice, the choice comes down to Flo’s content and life-stage breadth versus Clue’s deeper day-to-day logging.
Do Flo and Clue work on Android?
Yes, both run on iOS and Android, and Clue also works with Apple Watch. Our own app, Vera, is iOS only, so on Android these two are the mainstream options. Whichever platform you’re on, check the current listing, since features can differ slightly between versions.
Can I switch between Flo and Clue?
You can start logging in either app whenever you like, since both let you enter cycle data manually. If you leave Clue, you can request deletion by emailing trust@helloclue.com, and Clue says data is deleted within one month. Flo’s deletion path isn’t covered here, so check its current privacy policy. We haven’t verified an import or transfer tool for either app, so plan on manual entry.
A note on medical advice
This comparison is general information to help you choose an app, not medical advice, and it can’t diagnose anyone or guide treatment. Features, prices, and policies change, so check each app’s current listing before you decide. For anything about your own health or care, please speak with a qualified healthcare professional who knows your history.