Verdict
Flo predicts periods and fertile days from logged cycles and is free for basic tracking, with a Premium tier that adds a 24/7 Health Assistant. Mozilla scored it 7 out of 10 for privacy in July 2026 and found no symptom or pregnancy data going to ad partners, but Flo paid $8M in a 2026 US settlement over data it shared with Facebook and Google before 2019. Anonymous Mode removes the name and email from the account for anyone who wants extra distance.
Best for
Tracking periods and fertile days on a phone
Skip if
Anyone wanting health data kept only on the phone, or using it as contraception
Key facts
- Category
- Health, fitness & wellbeing
- Made by
- Flo Health UK Limited
- Based in
- United Kingdom
- Launched
- 2015
- Works on
- iPhone, Android, Web
- In the UK
- Yes
- Free plan
- yes: basic period and ovulation tracking; Premium adds insights, pregnancy features and the Health Assistant
What it does
- tracks periods, including irregular cycles
- predicts ovulation and the fertile window
- logs over 70 symptoms and moods
- tracks pregnancy and baby growth
- Anonymous Mode stores health data without personal identifiers
- makes cycle reports to share with a doctor
Ratings
What people say
individual reviewers who use Flo tend to praise its predictions, while a vocal group refuses to pay for it because of the 2016-2019 data sharing. In 2026 user reviews talk about Flo was dominated by the $59.5M US class-action settlement claim deadline rather than by its AI features. Store ratings of 4.7 from millions of ratings match the satisfied users more than the privacy critics.
“Flo is pretty damn accurate with my irregular periods it’s dope”
Individual user review, 25 April 2026 · source
“I personally wouldn’t advise it, mainly because of the privacy issues and the fact that Flo Health has a history of sharing/selling sensitive reproductive data.”
Individual user review, 30 December 2025 · source
“Flo relies heavily on algorithmic predictions that are largely based on population averages, not really your individual data or any method-specific logic.”
Individual user review, 30 December 2025 · source
“I used to use Flo premium and liked it.. if you sign up and then choose to cancel, they offer you a super deep discount”
Individual user review, 30 December 2025 · source
Press reviews
- BBC News 2026-07-19
Reporting Mozilla's tests, Flo and Clue 'scored relatively well thanks to real transparency and granular privacy controls' but collect far more health data than rivals and store it on their own servers (BBC article republished by The Star).
- CyberInsider 2026-07-17
Mozilla scored Flo 7/10, third of six trackers; researchers saw no symptom, fertility or pregnancy data sent to ad partners once optional settings were declined.
- Consumer Reports 2025-08-07
After the Meta jury verdict, urged past Flo users to send a formal data deletion request rather than only deactivating the account.
Privacy
- Trains on your data
- Uses cycle data with consent for machine-learning predictions and to suggest content including the Health Assistant (privacy policy, 31 Aug 2026); the policy does not mention training generative models, and whether the Health Assistant is generative is unknown
- Opt-out
- Health processing is consent-based and can be withdrawn; ad and analytics sharing (AppsFlyer, Firebase, TikTok Ad Manager) can be refused in app or device settings; Anonymous Mode unlinks name and email
- Retention
- Kept while the service is used; deleted after 3 years of inactivity; deletion requests handled within a month, up to 90 days for backups
- Incidents
- FTC order (June 2021) over sharing health data with Facebook, Google and others in 2016-2019; US class action where Flo paid $8M of a $59.5M settlement (preliminary approval April 2026, final hearing 29 Oct 2026); jury found Meta liable over the same data (Aug 2025). No UK ICO action found in searches.
- Age limit
- 16+ in the UK, EEA and Canada, 13+ elsewhere (privacy policy); UK App Store 12+, Google Play PEGI 3
Official videos
FAQ
Is Flo safe to use after the data-sharing case?
The sharing with Facebook and Google happened between 2016 and 2019 and led to a 2021 FTC order and a 2026 settlement. Mozilla's July 2026 tests found no symptom or pregnancy data going to ad partners once optional settings were declined.
Is Flo free?
Basic period and ovulation tracking is free. Premium adds tailored insights, pregnancy tools and the Health Assistant, on monthly or yearly plans.
What is Flo's Anonymous Mode?
It lets people use Flo without their name, email or technical identifiers linked to their health data. Some features, such as wearable syncing, do not work in that mode.
Can Flo be used as contraception?
Flo itself does not claim to be contraception, and a user reviews critic notes its predictions lean on population averages. Natural Cycles is the app that holds regulatory clearance for birth control, according to a 2026 Bearable comparison.
Flo or Clue?
Mozilla's 2026 tests scored Clue 8 out of 10 for privacy and Flo 7. Both store data on their own servers, and both were praised for transparency and privacy controls.
Scores are based on published evidence, not lab tests. How we score.
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