Clue vs Flo vs Natural Cycles: 2026 Comparison

Natural Cycles is the only one of the three with an FDA De Novo grant for contraception, so it suits people who want app-based birth control. Clue suits people who want a science-led, GDPR-based tracker; Flo suits people who want a large content library and community features. Veya is a tracker, not birth control.

By Veya Team • Published July 27, 2026 • Last reviewed October 24, 2026 • 9 min read • App Comparison

Full Transparency

This comparison is published by Holland Neurotech Inc., the company behind Veya. We've included Veya as a fourth option where relevant. We've done our best to compare each app fairly based on publicly available features, pricing, and user reviews. If Clue, Flo, or Natural Cycles is the better fit for you, use it. How we compared: we read the Clue, Flo, Natural Cycles and Stardust App Store listings first-hand on October 16, 2026 (ratings, prices, features, version notes), plus Natural Cycles' perimenopause page and the FDA records linked below.

This article is educational and not medical advice. Choosing a birth control method is a decision to make with a healthcare provider who knows your history.

Quick Answer

Here's how the three split by use case, with sources linked where we cite facts (App Store details are as of October 2026):

If you're weighing a third option, see the Veya fertility tracker.

Clue, Flo, and Natural Cycles show up in the same search results and the same "which app should I use" conversations, so it's easy to assume they're three competitors doing the same job. They aren't. Clue and Flo are both period and cycle trackers that predict your cycle from what you log. Natural Cycles is a birth control method that happens to live in an app, and it's the only one of the three with an FDA De Novo grant for preventing pregnancy.

That structural difference is the thing to understand before anything else here. Once it's clear, the rest of the comparison, free tiers, privacy, and how each handles an irregular cycle, is easier to reason about.

Which is better: Clue, Flo, or Natural Cycles?

They answer different questions. Natural Cycles is the one with an FDA De Novo grant for contraception ($149.99/year, 4.8 stars from about 30,000 ratings), Clue is the flexible logger for irregular cycles ($39.99/year, 4.8 from 406,000), and Flo is the community and content pick (Premium listed at $47.99 and $59.99, 4.7 from about 2 million), all as of October 2026. (NC, Clue, Flo)

Clue Flo Natural Cycles Veya
Best for Privacy and science Community and content App-based birth control All-in-one tracking
FDA-cleared as birth control Separate Clue Birth Control feature cleared 2021 (not on current listing)* No Yes (2018) No
How it works Calendar & symptom predictions AI-assisted calendar predictions Estimates ovulation by temperature Cycle + lifestyle tracking
Free tier Basic, with upsell prompts Core tools free No free tier listed Most features, no ads
Price (annual) $39.99/yr $47.99–$59.99/yr $149.99/yr (annual plan includes an NC° Band) ~$49.99/yr
Privacy GDPR-based (Berlin) FTC order and class action Regulated device Strong, no ads
Irregular cycles Flexible tracker Predictions weaken Weaker fit (needs regularity) Flexible tracker
App Store rating (Oct 2026) 4.8 from 406K ratings 4.7 from about 2M ratings 4.8 from about 30K ratings See App Store
Platform iOS + Android iOS + Android iOS + Android iOS only (+ web app)

* Clue received a 2021 FDA clearance (K193330) for a separate Clue Birth Control feature; the standard period tracker is not birth control. Prices come from each app's US App Store listing as of October 2026 (Clue, Flo, Natural Cycles). FDA status: De Novo grant DEN170052. Veya figures are our own.

Want more detail? Keep reading.

What changed in Clue, Flo, and Natural Cycles in 2026?

Natural Cycles now lists modules for pregnancy planning, pregnancy monitoring, postpartum and perimenopause and works with the NC° Band, Oura, WHOOP, Garmin and Apple Watch Series 8 or newer. Clue releases weekly (version 298.0), and Flo's Premium now includes a Symptom Checker and TTC fertility insights. All as of October 2026.

  • Natural Cycles (version 5.9.4): the listing says efficacy is 98% with perfect use and 93% with typical use, and that birth-control authorization applies only in certain regions, including the US, Canada, UK, EU/EEA and Australia (listing). Its NC° Perimenopause page says the app tracks symptoms, shows how they change over time and estimates a perimenopause stage with its NC° Menopause Algorithm, and that the same page frames it as wellness information, not a diagnosis.
  • Clue (version 298.0): Clue Plus is $9.99 for one month or $39.99 for one year, and its listing says Plus insights can be combined with temperature, sleep and heart rate data from a connected wearable (listing).
  • Flo (version 10.8.0): Premium is listed as including daily insights, a 24/7 Health Assistant, Secret Chats and TTC fertility insights (listing).

For the two trackers head to head, see Clue vs Flo; for how Natural Cycles works with a wearable, see Natural Cycles vs Oura.

What is the real difference between Clue, Flo, and Natural Cycles?

Clue predicts. It looks at the cycle and symptom data you log and estimates when your period and fertile window will probably happen. Clue has a science-led reputation (a 2016 Obstetrics & Gynecology study gave it the top score, 13 of 15, among 20 accurate, free cycle apps), but those estimates aren't measuring what your body is doing on a given day. Clue's standard tracker is not birth control; the company's separate Clue Birth Control feature received a 2021 FDA clearance, though its current listing doesn't list a birth-control mode.

Flo predicts too. It makes predictions from the cycle data you log, plus a content library and community features. Flo does not market itself as birth control, and its estimates carry the same limitation as Clue's: they're calendar-based, not a measurement of ovulation.

Natural Cycles measures. It uses your basal body temperature to confirm whether you've ovulated, then tells you whether today is a "green day" (not fertile) or a "red day" (use protection or abstain). That measurement approach is what the FDA reviewed when it granted Natural Cycles a De Novo request in 2018. In the FDA's decision summary, real-world data from 15,570 women gave a typical-use Pearl Index of 6.5 (about 6.5 pregnancies per 100 women per year) and a perfect-use Pearl Index of 1. On red days, it tells you to abstain or use a barrier method; the app itself doesn't physically prevent pregnancy, it tells you which days carry risk so you can act on it.

For general cycle and symptom tracking, Clue and Flo are the closer comparison to each other. If a hormone-free, app-based contraception method is what you want, Natural Cycles is the distinct option.

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Which free version should you start with?

Start with Clue or Flo if you want a free tier: both are free to download with core tracking included and deeper features behind a subscription. Natural Cycles is subscription-based, and we found no free tier on its listing ($21.99/month or $149.99/year as of October 2026).

Clue is free to download, and its listing prices Clue Plus at $39.99/year or $9.99/month, describing Plus as adding deeper analysis, advanced predictions, and personalized insights.

Flo is free to download with core tools included, per its listing. Annual Premium plans are listed at $47.99–$59.99 (as of October 2026), and Premium is listed as adding the virtual health assistant, Secret Chats, and in-depth pregnancy features.

Natural Cycles is priced as a subscription, with a free NC° Band offered on the annual plan per its listing. It's a regulated medical device you're paying to use as a contraceptive method, not a tracker with optional upgrades.

If a free option matters most, Clue or Flo is the place to start, and it's worth comparing pregnancy features in both apps before paying. Natural Cycles makes sense if you specifically want its contraception feature.

Which of the three is better for privacy?

It depends on which record you weigh. Clue is Berlin-based under EU GDPR, and Flo has an FTC order (June 2021) and a $59.5M class settlement with a hearing on October 29, 2026.

Clue leans on GDPR. It's headquartered in Berlin, and its App Store listing says your data is protected by strict European privacy law (GDPR). Apple's privacy label on the listing shows identifiers used for tracking, so read its privacy policy.

Flo has a documented enforcement history. In June 2021 the FTC finalized an order against Flo over allegations that it shared sensitive health data with companies including Facebook and Google despite promising privacy; the order requires consent before sharing health information and carried no fine. A separate class action over the same 2016–2019 data sharing reached a proposed $59.5M settlement with Google, Flo and Flurry (Flo’s share: $8M; the defendants deny wrongdoing). It received preliminary approval in April 2026, with a final approval hearing set for October 29, 2026. Flo has since added Anonymous Mode, which its listing describes as using the app without personal identifiers linked to your health data. Whether that's enough is a personal call, but the history is worth knowing before you hand over your data.

Natural Cycles is a regulated medical device (see its FDA De Novo grant), and its App Store seller is NaturalCycles Nordic AB. We didn't verify its data practices, so as with any health app, read the current privacy policy to see exactly what's collected and shared.

Read each company's current privacy policy and decide what you're comfortable with, especially if app-based contraception data is part of your concern.

Which of the three handles irregular cycles?

Clue is the more forgiving choice for irregular cycles: its App Store listing says you can track symptoms even without regular bleeding. Flo predicts from logged history, and Natural Cycles estimates ovulation from temperature, which depends on consistent daily measurement. A tracker and a contraceptive method answer "irregular" differently.

As trackers, Clue and Flo both predict from calendar and symptom history. Calendar-based predictions generally get less reliable when cycles vary a lot, and neither app can fix that. Clue's detailed symptom logging may suit people whose cycles aren't textbook, since you can record whatever pattern shows up, but we haven't seen a head-to-head test.

Natural Cycles works differently, and that changes the calculus. Instead of guessing fertile days from a calendar, it estimates ovulation retrospectively from your daily temperature. That's an advantage in principle, but temperature-based methods generally work best with fairly regular cycles and consistent measurement timing, so it may be a weaker fit if your cycles vary a lot. Disrupted sleep, travel, and inconsistent measurement timing can degrade the temperature signal it depends on.

If your cycles are unpredictable and you mainly want to understand them, a flexible tracker like Clue is the more forgiving choice day to day. If you're evaluating Natural Cycles specifically as a method and your cycles are irregular, that's a conversation to have with a healthcare provider about whether temperature-based tracking will work reliably for you.

What About Stardust?

Stardust comes up in the same searches because it's a well-rated period tracker: its App Store listing shows 4.8 stars from about 119K ratings (as of October 2026). Like Clue and Flo, it's a tracker, not a contraceptive, so it sits closer to that pair than to Natural Cycles.

Per the listing, Stardust pairs cycle tracking with daily insights, moon and zodiac features, and partner sharing. It's free to download with in-app subscriptions, includes a week-by-week Pregnancy Mode, and says "We never sell or share your personal health information" (Apple's privacy label on the same listing still shows identifiers used for tracking). We didn't verify its Android availability.

In short: if Clue and Flo feel clinical or like a chore, Stardust is built around daily insights and a more playful design. It's not a substitute for Natural Cycles if what you actually want is app-based contraception.

Is there a fourth option?

Natural Cycles sells its wearable temperature as a paid bundle built for contraception, and neither Flo nor Clue has basal temperature at all.

Veya reads temperature from the Apple Watch, Oura or Garmin you already own and uses it for fertility awareness. You can also log LH tests and cervical mucus by hand, and the fertile window updates as the data comes in. There is no morning thermometer to remember. That matters if you want to understand your cycle without paying for a method built around contraception. You decide how much to log, and the app works with what you have.

Checked October 24, 2026 against the current App Store listings and Veya's web app.

Veya is not contraception, and the full app is iPhone only, with a web app for everything else.

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Should you choose Clue, Flo, Natural Cycles, or Veya?

The right one depends on what you need most. Natural Cycles fits app-based contraception ($149.99/year), Clue fits flexible logging and privacy-minded users ($39.99/year), Flo fits community and content (Premium listed at $47.99 and $59.99), and Veya fits cycle data next to mood, sleep and nutrition. Prices as of October 2026. Choose by situation:

Choose Clue if:

  • EU privacy law (GDPR) matters to you in a tracker
  • You want a clean, science-backed tracker without extra noise
  • Your cycles are irregular and you want flexible logging rather than rigid predictions
  • You don't need the app to double as birth control

Choose Flo if:

  • You want a large community and content library
  • You want pregnancy checklists and guidance (check which parts are free)
  • You're comfortable with Flo's privacy history, or you'll use Anonymous Mode

Choose Natural Cycles if:

  • You want app-based birth control backed by an FDA De Novo grant
  • You prefer a hormone-free method and have talked it through with a provider
  • Your cycles are reasonably regular and your sleep routine is consistent
  • You're willing to pay and take a daily temperature reading (or already own a compatible wearable)

Choose Veya 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 a free tier with no ads
  • You're on iOS (or okay using the web app on other platforms)

Frequently asked questions about Clue, Flo, and Natural Cycles

How do Clue, Flo, and Natural Cycles compare?

All three track your cycle, but they are built for different goals. Clue is science-led (Clue Plus $39.99/year), Flo has a large content library and community (Flo Premium Premium listed at $47.99–$59.99), and Natural Cycles is the only one of the three with an FDA De Novo grant for contraception, using basal body temperature ($21.99/month or $149.99/year, as of October 2026). For general cycle and symptom tracking, Clue and Flo are closer competitors. If you want a hormone-free, app-based contraception method, Natural Cycles is the distinct option.

Clue vs Flo vs Natural Cycles: which has the best free version?

Clue and Flo are both free to download with in-app purchases, while Natural Cycles is subscription-based ($21.99/month or $149.99/year as of October 2026; we didn't find a free tier listed). Between Clue and Flo, Flo's listing puts in-depth pregnancy features in Premium, and Clue's listing doesn't say which plan includes pregnancy mode, so compare them in the app. If a free option matters most, Clue or Flo is the place to start. Natural Cycles makes sense if you specifically want its contraception feature.

Which is best for privacy: Clue, Flo, or Natural Cycles?

Each has a different footing. Clue is headquartered in Berlin and says its data is protected by GDPR. Flo settled FTC allegations in 2021 and is part of a proposed $59.5M class action settlement (with Google and Flurry; preliminary approval April 2026, final approval hearing October 29, 2026) over sharing health data with companies including Facebook and Google, though it has since added Anonymous Mode. Natural Cycles is an FDA-regulated medical device, so review its current privacy policy if app-based contraception data is your concern.

Which app handles irregular cycles best: Clue, Flo, or Natural Cycles?

As trackers, Clue and Flo both predict from calendar and symptom history, and calendar-based predictions generally get less reliable when cycles vary a lot. Clue's detailed symptom logging may suit people whose cycles aren't textbook, though we haven't seen a head-to-head test. Natural Cycles works differently: it estimates ovulation retrospectively from your daily temperature, but temperature-based methods generally work best with fairly regular cycles and consistent measurement timing. If your cycles are unpredictable and you mainly want to understand them, a flexible tracker is more forgiving. If you want a method, talk to a provider about whether temperature-based tracking suits your cycles.

Is Clue or Flo better for irregular cycles?

Clue's App Store listing says you can track symptoms even without regular bleeding, which is why it is a common pick for irregular cycles. Flo predicts from your logged history and keeps its Symptom Checker and TTC insights in Premium. Calendar-based predictions generally get less reliable as cycles vary, and neither app diagnoses anything.

Does Natural Cycles work for perimenopause?

Natural Cycles lists a perimenopause module. Its NC Perimenopause page says the app tracks symptoms, shows how they change over time and estimates a perimenopause stage with its NC Menopause Algorithm, optionally with a wearable. The same page says it offers wellness information, not a diagnosis, and its birth-control authorization is separate from this mode.

How does Stardust compare to Clue, Flo, and Natural Cycles?

Stardust is a period tracker, not birth control, so it sits closer to Clue and Flo than to Natural Cycles. Its listing describes daily insights, moon and zodiac features, partner sharing, and a week-by-week Pregnancy Mode, and the app is free to download with in-app subscriptions. Its listing says “We never sell or share your personal health information.”

Can you use Clue, Flo, or Stardust as birth control?

Clue, Flo, and Stardust are period and cycle trackers, and their standard tracking is not contraception. (Clue received a 2021 FDA clearance for a separate Clue Birth Control feature, which its current listing doesn't list.) Natural Cycles is the only app in this comparison with an FDA De Novo grant for preventing pregnancy, and it works differently: it estimates ovulation retrospectively from your daily temperature rather than estimating fertile days from a calendar.

Want the Detailed Head-to-Head?

This guide covers all three (plus Stardust) at once, but if you're weighing two of them specifically, our pairwise comparisons go deeper on each matchup.

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