Clue vs Flo: Which Period Tracker Is Actually Better?
You've narrowed it down to two apps. Clue is the science-focused one. Flo is the popular one. But which one actually works better for you? Here's what we found after comparing them on accuracy, privacy, features, and price.
Full Transparency
This comparison is published by Holland Neurotech Inc., the company behind Go Go Gaia. We've included Go Go Gaia as a third option where relevant. We've done our best to compare each app fairly based on publicly available features, pricing, and user reviews. If Clue or Flo is the better fit for you, use it.
Quick Answer
- If privacy matters most: Go with Clue. It's based in Germany, subject to GDPR, and has a clean privacy record.
- If you want health education and community: Go with Flo. It has 420M+ downloads, thousands of articles, and active discussion forums.
- If you want all-in-one tracking (cycle + mood + fitness + nutrition + habits) for free: Try Go Go Gaia.
Clue and Flo are the two biggest period trackers in the world. If you're trying to pick one, you're not alone. Millions of people search "Clue vs Flo" every year, and the answer isn't as simple as "this one is better."
They're built for different priorities. Clue leans into science and privacy. Flo leans into community and content. Both have trade-offs. We'll walk through exactly what you get with each, what you don't, and introduce a third option you might not have considered.
The Short Version
If you're in a rush, here's the quick breakdown:
| Clue | Flo | Go Go Gaia | |
|---|---|---|---|
| Best for | Privacy and science | Community and content | All-in-one tracking |
| Platform | iOS + Android | iOS + Android | iOS only (+ web app) |
| Free tier | Basic, with upsell prompts | Basic, with ads | Most features, no ads |
| Premium price | ~$39.99/year | ~$49.99/year | ~$49.99/year |
| Privacy | Excellent (GDPR) | Concerning history | Strong, no ads |
| Wearables | Oura, Fitbit, WHOOP (paid) | Apple Watch only | Apple Watch, Oura, Garmin |
| Languages | 23 | 22 | 16 (web app) |
Want more detail? Keep reading.
Clue: What You Get
Clue was founded in Berlin in 2012. It's the tracker that scientists and privacy advocates tend to recommend, and there are good reasons for that.
Features
- Cycle tracking with science-backed predictions
- 30+ symptom tracking categories
- Gender-neutral, clinical design
- Pregnancy mode (Clue Plus only)
- Wearable sync with Oura, Fitbit, and WHOOP (Clue Plus only)
- Available in 23 languages
- Transparent algorithm documentation
Strengths
Privacy is Clue's biggest advantage. It's based in Germany, subject to strict EU GDPR privacy laws, and has publicly committed to not sharing user data with US authorities. If privacy is your top priority, Clue is the safest choice on this list.
The design is clean and no-nonsense. No pink flowers. No "girl talk" copy. Clue uses a clinical, gender-neutral approach that a lot of people prefer. The journal Obstetrics & Gynecology has ranked it among the top tracking apps.
Science-backed predictions. Clue publishes research and is transparent about how its algorithms work. You can read about the methodology behind your predictions, which is rare for consumer health apps.
Limitations
The free tier has gotten thinner over time. Basic cycle tracking is free, but pregnancy mode, wearable sync, and deeper insights all require Clue Plus (~$39.99/year). Free users see frequent full-screen upgrade prompts.
No nutrition, fitness, or habit tracking. Clue is a cycle tracker. If you want to log meals, workouts, or daily habits alongside your cycle, you'll need a second app.
Wearable integration is premium-only. Oura, Fitbit, and WHOOP sync are locked behind Clue Plus. There's no Apple Watch or Garmin support at any tier.
No AI assistant. Clue doesn't offer a chatbot or AI-powered health Q&A.
Pricing
Free: Basic cycle and symptom tracking, with upgrade prompts.
Clue Plus: ~$39.99/year. Adds pregnancy mode, wearable sync, deeper insights, and an ad-free experience.
Download: Available on iOS and Android
Flo: What You Get
Flo is the most downloaded period tracker in the world, with over 420 million downloads. It's the app your friends are probably using. That popularity comes with real advantages and some real baggage.
Features
- Cycle tracking with AI-powered predictions
- Thousands of health articles reviewed by 100+ medical professionals
- AI health assistant (Flo Premium)
- Secret Chats for anonymous community discussions
- Pregnancy mode with week-by-week tracking
- Apple Health integration
- Apple Watch companion app
Strengths
The content library is massive. Flo has thousands of articles covering everything from PMS to fertility to menopause, all reviewed by medical professionals. If you want to learn about your health while tracking it, Flo offers more educational content than any other tracker.
The community is the biggest in the space. With 420M+ downloads, Flo's Secret Chats give you access to anonymous discussions with millions of other users. If you have a question about a weird symptom at 2am, someone in the Flo community has probably experienced it too.
Free pregnancy mode. Unlike Clue, Flo includes pregnancy tracking in its free tier. You get week-by-week fetal development updates and pregnancy-specific content without paying.
Limitations
Privacy is the big concern. Flo settled with the FTC in 2021 for sharing period and pregnancy data with Facebook and Google without user consent. A $56 million class action settlement followed in 2025. Flo has since added Anonymous Mode and says it has changed its practices. The track record is still worth knowing.
Ads and paywalls. Free users see ads, and a growing number of features and articles are locked behind Flo Premium (~$49.99/year).
No nutrition, habit, or sleep tracking. Like Clue, Flo is focused on cycle tracking. You can't log meals, track habits, or monitor sleep quality within the app.
Limited wearable support. Flo has an Apple Watch companion app, but there's no Oura, Garmin, or Fitbit integration.
Pricing
Free: Basic cycle and symptom tracking, pregnancy mode, community access. Includes ads.
Flo Premium: ~$49.99/year. Adds AI assistant, ad-free experience, advanced insights, and full content library access.
Download: Available on iOS and Android
The Third Option: Go Go Gaia
If you've been reading the Clue and Flo sections thinking "I wish one app did all of this," that's where Go Go Gaia comes in. It's a newer app that takes a different approach: instead of being a cycle tracker with a few extras, it's built to track your entire health picture in one place.
What It Adds
- Cycle tracking with automatic phase detection and fertility predictions
- Mood, sleep, fitness, and nutrition tracking built in
- Custom habit tracking with auto-updating streaks
- Wearable sync with Apple Watch, Oura Ring, and Garmin
- Correlation insights showing how your lifestyle affects your cycle
- Pregnancy mode with trimester tracking
- PCOS and perimenopause support
- 1-click logging for fast daily tracking
- No ads, no data selling
Why Consider It
The main selling point is that you don't need three apps. Instead of Clue for your cycle, MyFitnessPal for food, and a separate mood tracker, Go Go Gaia puts it all in one place. And then it shows you the connections, like how your sleep affects your mood in the luteal phase, or how exercise impacts your PMS symptoms.
The free tier includes most features with no ads. That's a genuine differentiator when both Clue and Flo are pushing harder on paywalls.
Honest Limitations
- iOS only. There's no Android app. A web app is available for other platforms, but the full experience is iPhone-only right now.
- Smaller community. Go Go Gaia doesn't have Flo's 420M users or Clue's decade-long user base. If in-app community matters to you, this isn't the place for it yet.
- Newer app. It hasn't been around as long as Clue (2012) or Flo (2015). That means fewer user reviews and a shorter track record.
- AI features are premium. The AI assistant (Ask Gaia) requires a subscription (~$9.99/month or ~$49.99/year).
Pricing
Free: Cycle, mood, sleep, fitness, nutrition, and habit tracking. No ads.
Premium: ~$9.99/month or ~$49.99/year for AI features and advanced insights.
Download: Available on iOS App Store
Side-by-Side Feature Comparison
Here's every major feature compared across all three apps. Check marks mean the feature is included, locks mean it requires a paid subscription, and X marks mean it's not available.
| Feature | Clue | Flo | Go Go Gaia |
|---|---|---|---|
| Cycle tracking | ✅ | ✅ | ✅ |
| Fertility tracking | ✅ | ✅ | ✅ |
| Pregnancy mode | 🔒 Paid | ✅ | ✅ |
| Mood tracking | ⚠️ Basic | ⚠️ Basic | ✅ Detailed |
| Sleep tracking | ❌ | ❌ | ✅ |
| Nutrition tracking | ❌ | ❌ | ✅ |
| Fitness tracking | ❌ | ❌ | ✅ |
| Habit tracking | ❌ | ❌ | ✅ |
| Wearable integration | 🔒 Paid (Oura, Fitbit, WHOOP) | ⚠️ Apple Watch only | ✅ Apple Watch, Oura, Garmin |
| AI assistant | ❌ | 🔒 Paid | 🔒 Paid |
| Community | ❌ | ✅ Largest | ❌ |
| Privacy practices | ✅ Excellent (GDPR) | ⚠️ FTC/class action history | ✅ Strong, no ads |
| Free tier quality | ⚠️ Limited + upsells | ⚠️ Limited + ads | ✅ Generous, no ads |
| Price (annual) | ~$39.99/yr | ~$49.99/yr | ~$49.99/yr |
Which Should You Choose?
There's no single "best" app. It depends on what you care about most. Here's the honest breakdown:
Choose Clue if:
- Privacy is your top priority. Clue's GDPR compliance and clean track record are the gold standard
- You want a clean, science-backed tracker without extra noise
- You prefer a gender-neutral design
- You need Android support
- You're comfortable with a focused cycle tracker (no nutrition or fitness logging needed)
Choose Flo if:
- You want access to the largest community of people tracking their cycles
- Health education and articles are important to you
- You want free pregnancy tracking
- You need Android support
- You're comfortable with Flo's privacy practices (or willing to use Anonymous Mode)
Choose Go Go Gaia if:
- You want cycle, mood, sleep, fitness, nutrition, and habit tracking in one app
- You track with a wearable (Apple Watch, Oura, or Garmin) and want that data connected to your cycle
- You want to see how your lifestyle habits affect your cycle and symptoms
- You want a generous free tier with no ads
- You're on iOS (or okay using the web app on other platforms)
Privacy: The Elephant in the Room
Period tracking data is sensitive. It includes information about your cycle, fertility, and pregnancy status. Here's where each app stands:
Clue: The Privacy Leader
Clue is based in Berlin, Germany, which means it's subject to EU GDPR regulations. These are some of the strictest privacy laws in the world. Clue has publicly stated it will not share user data with US authorities and publishes transparency reports. If you want the most private period tracker available, Clue is it.
Flo: A Complicated History
In 2021, the FTC settled with Flo for sharing users' period and pregnancy data with Facebook and Google for advertising purposes. This happened without user consent. In 2025, a $56 million class action settlement followed over the same data-sharing practices.
Flo has since added Anonymous Mode and says it has reformed its data practices. These are real steps. But the fact that it happened at all is something worth knowing before you hand over your health data.
Go Go Gaia: Privacy-Focused, Smaller Scale
Go Go Gaia doesn't run ads and doesn't sell user data. The privacy practices are strong. That said, it's a newer, smaller company without the years of public scrutiny that Clue has gone through. There's no GDPR certification (it's a US-based company), but the no-ads, no-data-selling approach is a meaningful commitment.
Frequently Asked Questions
Is Clue or Flo more accurate?
Both apps are reasonably accurate for regular cycles. After 3+ months of data, they typically predict your period within 1-3 days. Flo uses AI-powered predictions while Clue uses a science-backed algorithm. For irregular cycles, neither app is great. Calendar-based predictions drop to roughly 18% accuracy when cycles vary a lot. If your cycles are unpredictable, focus on tracking patterns rather than trusting predictions from either app.
Which is better for privacy, Clue or Flo?
Clue, by a wide margin. It's based in Germany, subject to strict EU GDPR laws, and has publicly committed to not sharing data with US authorities. Flo was caught sharing period and pregnancy data with Facebook and Google, leading to an FTC settlement in 2021 and a $56 million class action settlement in 2025. Flo has added Anonymous Mode since then, but the track record speaks for itself.
Is Clue really free?
The basic version is free. You can track your period and log symptoms without paying. But pregnancy mode, wearable sync, deeper insights, and most content are locked behind Clue Plus at about $39.99 per year. The free version also shows frequent full-screen prompts asking you to upgrade, which some users find annoying.
Does Flo sell your data?
Flo was caught sharing sensitive health data, including period dates and pregnancy intentions, with Facebook and Google for advertising. This led to an FTC settlement in 2021 and a $56 million class action settlement in 2025. Flo says it has changed its practices and added Anonymous Mode. Whether that's enough depends on how you feel about it.
Can I use Clue or Flo for pregnancy?
Both apps offer pregnancy modes. Flo includes pregnancy tracking for free, with weekly fetal development updates and educational articles. Clue requires Clue Plus (about $39.99/year) for pregnancy mode. If pregnancy tracking matters and you don't want to pay, Flo has the advantage here.
What's a good alternative to Clue and Flo?
Go Go Gaia is worth considering if you want more than just cycle tracking. It includes mood, sleep, fitness, nutrition, and habit tracking in one app. It syncs with Apple Watch, Oura Ring, and Garmin, and shows you correlations between your lifestyle and your cycle. Most features are free with no ads. The downsides: it's iOS only (a web app is available for other platforms), it's a newer app, and the community is much smaller than Clue or Flo.
Want to See More Apps Compared?
This guide focused on Clue vs Flo, but there are other great options out there. If you want the full picture, check out our complete comparison of 6 period tracking apps, including Ovia, Natural Cycles, and more.
Read the full comparison: Best Period Tracker App 2026 (6 Apps Compared) →
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- Period Tracking Guide: How to Track Your Cycle and Why It Matters
- Best Period Tracker App 2026: Clue vs Flo vs Ovia (6 Apps Compared)
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