Flo vs Clue: Which Period Tracker Is Better in 2026?
The two most-downloaded period trackers predict the same way. Where they differ is what you get free, who holds your data, and whether anyone else can see the calendar.
Flo vs Clue comes down to breadth versus control: Flo gives you more free features and a much larger health library, while Clue gives you more say over its predictions and over where your data goes. On the question most people actually ask, which one predicts better, they tie, because both work from the period dates you log. This guide compares the two on accuracy, price, privacy record, partner sharing and switching cost, then closes with a two-minute way to choose.
Which one is better, Flo or Clue?
Flo is better if you want the most features without paying: period and ovulation predictions, more than 80 symptoms to log, a large expert-written library and a community space are all in the free tier. Clue is better if you want fewer, cleaner tools and more control: you can hide its predictions, its data handling is governed by German and EU law, and its subscription is the cheaper of the two.
If a partner is part of the decision, neither is built for that, and the section on partner sharing below explains what each offers and where a third option fits.
The rest of this guide is the evidence behind those two sentences.
Flo vs Clue at a glance
Is Clue more accurate than Flo?
No, and Flo is not more accurate than Clue either. Both apps predict your next period by applying your past cycle lengths to your last logged start date, so both are close when your cycles are steady and both miss when they are not. The difference is how each behaves when the prediction is wrong.
Flo’s own help page recommends adding the last 12 months of periods, or at least three cycles, before trusting its predictions. Clue’s Plus tier extends predictions 12 cycles ahead, and for people whose cycles vary too widely for predictions to help, Clue built a setting to hide predictions entirely. Clue also reports that a study published in Obstetrics and Gynecology, the journal of the American College of Obstetricians and Gynecologists, scored it 13 out of 15, the highest of the apps evaluated, on accuracy, features and functionality.
Where both fall down is ovulation. In the largest real-world cycle analysis, the phase before ovulation ranged from 10 to 30 days, and the Apple Women’s Health Study found a standard deviation of 6.1 days in cycle length. A calendar cannot see that variation, so neither app’s fertile-window shading should be treated as a measurement. The research is laid out in how accurate period tracker apps really are, and Flo’s specific claims are tested in what Flo’s predictions get right and wrong.
What is free, and what costs money?
Flo’s free version is unusually generous. Its help page lists period and ovulation predictions, more than 80 symptoms to track, a health library and the Secret Chats community. Flo Premium adds cycle-pattern analysis, expert-led video courses and content, and is sold as a monthly or yearly subscription through the App Store. Flo says 6.6 million members have signed up for Premium.
Clue’s free tier covers core tracking and predictions. Clue Plus is $9.99 a month or $39.99 a year, and unlocks predictions 12 cycles ahead, PMS and fertile-window predictions, the Conceive, Pregnancy and Perimenopause modes, Clue Connect for sharing with a partner, unlimited custom tags and priority support.
The practical read: a Flo user who never pays gets more than a Clue user who never pays. A Clue user who pays gets a cheaper yearly bill and the app’s most useful features.
Clue vs Flo on privacy: the record, not the reputation
Clue vs Flo on privacy is the one place the two have genuinely different histories, and it is worth reading the record rather than the reputation.
Flo’s record has two public chapters. In January 2021 Flo Health settled Federal Trade Commission allegations that it had shared users’ health information, including the fact of a pregnancy, with analytics providers at Facebook and Google after promising to keep it private; the settlement required an independent privacy review and user consent before sharing. In August 2025 a California jury found Meta violated the California Invasion of Privacy Act in a class action over Flo data that had been running since 2021; Google and one analytics firm settled before trial.
Flo’s answer to that history is Anonymous Mode, available to every user at no cost, which lets you use the app with no name, email, IP address or other identifier linked to your health data. Mozilla’s July 2026 review still scored Flo 7 out of 10, noting that sharing with ad and analytics partners is optional and that turning it off worked in testing.
Clue is made by BioWink GmbH in Berlin, and its privacy policy states that its data handling meets German and EU legal requirements, with a named data protection officer. Mozilla scored Clue 8 out of 10, crediting it for handling each data-sharing choice separately and keeping the settings editable after signup.
Flo has a documented history and a documented fix. Clue has a jurisdiction. Which of those reassures you more is the real privacy question.
For the wider field, including apps that never send data off the phone at all, see which period trackers keep your data private.
Which is better if a partner follows along?
Neither app was designed around a partner, but both bolt it on. Flo for Partners gives a partner basic access free, with cycle position, predictions and general tips. Clue Connect shares phase dates only and requires Clue Plus on the cycle owner’s side, so the partner sees when, not what to do.
Otty is the third option here, and the reason we wrote this guide. It is a period tracker built for couples that works just as well solo: the person tracking gets phase names in plain words, and a partner who is invited sees their own view with one specific daily tip, opted in item by item, as described on the share-your-cycle page. It is iOS only, with a free 7-day trial and then a subscription, and its predictions are calendar estimates like everyone else’s.
If the partner question is the deciding one, the five apps that handle it are compared in the best period tracker for couples guide.
Can I transfer my Flo data to Clue?
Not directly. Clue’s support page states that there is no direct way to import data from other period-tracking apps, and its privacy policy lists Apple Health as the supported import integration. The same is true in the other direction. Switching therefore means re-entering history, and the good news is that you need far less of it than you think.
The full walkthrough for leaving Flo specifically, including what to export first, is in the Flo alternatives guide.
How to choose in two minutes
Pick Flo if you want to log a lot of symptoms, read a lot, and pay nothing. Pick Clue if you want a quieter app, the option to hide predictions on a cycle that will not hold a rhythm, and a cheaper yearly price when you do subscribe. Pick either if your only goal is knowing roughly when your next period starts, because on that question they are the same app in two outfits.
Pick something else if you need ovulation timing, which needs temperature or hormone data rather than a calendar, or if the calendar needs to be shared with someone who should know what helps, which is what Otty is for.
