Flo vs Natural Cycles vs Apple Health for Cycle Tracking (2026)
Natural Cycles is the one of these three that the FDA has authorized as birth control. Flo is a broad cycle tracker with perimenopause and pregnancy modes, and Apple Health's Cycle Tracking is free and built into the iPhone. This guide compares what each does, what it costs, what temperature inputs Natural Cycles accepts, and what each says about privacy, using each company's own pages as of October 2026.
Full Transparency
This comparison is published by Holland Neurotech Inc., the company behind Veya. Veya is included as one column, and we say plainly where it differs. We've described Flo, Natural Cycles and Apple Health from their own published pages. If one of them fits you better than Veya, use it.
Quick Answer
These three do different jobs, so the question is which job you want done.
- An FDA-authorized birth control app: Natural Cycles. The FDA granted it a De Novo request on August 10, 2018, and it costs $149.99 a year or $21.99 a month on the App Store as of October 2026.[1][2]
- A broad cycle tracker with a free tier: Flo. Its listing is free with in-app purchases, and it describes Pregnancy Mode, a Perimenopause Score and an Anonymous Mode.[3]
- Free and built in: Apple Health. Cycle Tracking can estimate ovulation from wrist temperature on Apple Watch Series 8 or later, and Apple says it should not be used as birth control.[4]
The Short Version
Here is how the three line up on the points people ask about most.
| Natural Cycles | Flo | Apple Health | |
|---|---|---|---|
| FDA status | De Novo granted Aug 10, 2018[1] | Not described as birth control | Says not for birth control[4] |
| Inputs | Thermometer, Oura, WHOOP, Garmin, Apple Watch S8+[2] | Logged data, Apple Watch compatible[3] | Logs, plus wrist temperature (Watch S8+, Ultra)[4] |
| Price | $21.99/mo or $149.99/yr[2] | Free, Premium purchases listed up to $59.99[3] | Free, built in[4] |
| Perimenopause | NC° Perimenopause mode[2] | Perimenopause Score, Menopause Timeline[3] | Menopause stages can be tracked[4] |
| Privacy record | Not reviewed here | FTC order, 2021[5] | Encrypted, end to end in iCloud with 2FA[4] |
What Does "FDA Cleared" Mean for Natural Cycles?
It means the FDA reviewed Natural Cycles as software for preventing or planning pregnancy and granted a De Novo request on August 10, 2018. It does not mean any app can stop a pregnancy, and it says nothing about Flo or Apple Health, which make no such claim.[1]
The FDA's database lists the device as "device, fertility diagnostic, contraceptive, software application" under regulation 884.5370.[1] The decision summary reports a typical-use Pearl Index of 6.5 and a perfect-use Pearl Index of 1, from data on 15,570 women.[6] A Pearl Index counts pregnancies per 100 users per year, so 6.5 means about 6.5 per 100 under typical use.
Two things are worth keeping straight. The app tells you which days carry risk, and acting on that is up to you. And the FDA later cleared temperature input from the Oura ring (June 2021) and Apple Watch (August 2023) for use with Natural Cycles through separate 510(k) decisions.[7][8] Our Natural Cycles vs Oura guide goes through those.
What Temperature Inputs Does Natural Cycles Accept?
Natural Cycles' App Store listing says it works with a basal thermometer, Oura Ring, WHOOP, compatible Garmin devices, or Apple Watch Series 8 or newer. New annual subscribers receive a free NC° Band.[2] Its devices page adds that you can use only one device at a time.[9]
The devices page also lists what each costs beyond the app: the NC° Band needs only a Natural Cycles subscription, while Oura Gen3 or later and WHOOP also need their own memberships. It recommends about five temperature readings a week, and says to switch devices only at the start of a new cycle.[9]
Linking is not automatic. An Apple Watch feeds Apple's own Cycle Tracking by default, but it only feeds Natural Cycles after you connect it inside that app. The Oura vs Apple Watch vs Natural Cycles guide covers that in more detail.
How Does Flo Predict Your Cycle?
Flo predicts from the dates and symptoms you log, and its listing describes the app as free with in-app purchases. Premium adds fertility insights, a 24/7 Health Assistant and daily insights. It also lists Pregnancy Mode, a Perimenopause Score and a Menopause Timeline.[3]
Flo's listing doesn't describe contraceptive use, and it presents predictions as coming from what you log. It shows 2M ratings averaging 4.7 out of 5.[3] It also describes an Anonymous Mode that uses the app without personal identifiers linked to your health data. For a side-by-side with the other two, see Flo vs Natural Cycles, Clue vs Flo vs Natural Cycles and Flo vs Apple Health Cycle Tracking.
What Does Apple Health Cycle Tracking Do?
Apple's Cycle Tracking logs periods, symptoms, spotting and basal body temperature, and it can use wrist temperature to estimate when you likely ovulated. That needs Apple Watch Series 8 or later or any Apple Watch Ultra, and ovulation estimates are available only in certain countries or regions.[4]
Apple calculates the fertile window by subtracting 13 days from the estimated next cycle start, which a positive ovulation test can shift and heart rate data can personalize. You can turn on period and fertile-window notifications as well as cycle deviation alerts. Apple states that Cycle Tracking should not be used as a form of birth control or to diagnose a health condition.[4] We couldn't tell from Apple's page which of these features changed with iOS 26, so we don't attribute any of them to that release.
What Do They Cost?
As of October 16, 2026, Natural Cycles lists Monthly $21.99 and Annual $149.99, Flo's in-app purchases run up to $59.99, and Apple Health Cycle Tracking is free and built in.[2][3]
Natural Cycles has no free tier on its App Store listing, and the annual plan includes the NC° Band. Flo's listing shows several Premium purchases from $1.99 to $59.99 without labelling the billing periods, so check the paywall in the app. Flo also lists Flo Birth Control Reminder at $43.99, a separate purchase. For reminder-style apps, see our birth control reminder app guide.[3] An Oura or WHOOP membership is an extra cost if you connect those to Natural Cycles.[9]
What Does Each One Say About Privacy?
Flo settled with the FTC in 2021 after the agency alleged it shared health data from millions of users with outside firms despite privacy promises. Apple says Cycle Tracking data is encrypted and, with two-factor authentication, end-to-end encrypted in iCloud. We did not review Natural Cycles' privacy policy for this page.[4][5]
The FTC finalized its order on June 22, 2021. It requires Flo to get affirmative consent before sharing health information, obtain an independent review of its privacy practices, and notify affected users.[5] Flo's listing now describes an Anonymous Mode.
Where Does Veya Fit?
Veya is a tracker, not birth control, and it isn't FDA-authorized for contraception. It reads Apple Watch, Oura and Garmin data and puts cycle tracking next to mood, sleep, fitness and nutrition across 350+ metrics, with no ads.
It is iOS only, with a web app for other platforms. It doesn't have Flo's community size or rating count, Natural Cycles' regulatory authorization, or the zero-install convenience of Apple Health. Natural Cycles is the one in this comparison with FDA authorization as birth control.
How We Compared
First-hand, on October 16, 2026, we opened the App Store listings for Natural Cycles and Flo, Natural Cycles' site and devices page, the FDA's De Novo database entry, Apple's Cycle Tracking support page and the FTC's press release. We used no review sites or secondary summaries. Anything we couldn't read from a primary page is marked as not reviewed. No company paid for placement or reviewed this page.
Frequently Asked Questions
Is Natural Cycles better than Flo?
They do different jobs. Natural Cycles is a subscription app that the FDA authorized in 2018 as software for preventing or planning pregnancy, and Flo is a cycle tracker that doesn't claim that use. Which is better depends on whether you want a method or a tracker.
Does Natural Cycles work with Apple Watch?
Natural Cycles' App Store listing says it works with Apple Watch Series 8 or newer, alongside a basal thermometer, Oura Ring, WHOOP and compatible Garmin devices. You have to connect the watch inside Natural Cycles, and you can use only one device at a time.
Is Apple Health Cycle Tracking enough on its own?
It covers logging, predictions, a fertile-window estimate and, with a compatible Apple Watch, ovulation estimates from wrist temperature. Apple says it should not be used as birth control or to diagnose a condition, so it suits people who want free, built-in tracking.
What does FDA cleared mean for a period app?
It means the FDA reviewed that specific software for its stated use. Natural Cycles received a De Novo grant on August 10, 2018 for preventing or planning pregnancy. It says nothing about apps that never made that claim, and it isn't a promise that pregnancy won't happen.
What happened with Flo and the FTC?
The FTC announced a proposed settlement on January 13, 2021 and finalized the order on June 22, 2021. It alleged Flo shared sensitive health data with firms including Facebook and Google despite privacy promises, and the order requires affirmative consent for sharing.
How much does Natural Cycles cost compared with Flo?
As of October 2026, Natural Cycles lists $21.99 monthly and $149.99 annually on the App Store. Flo is free to download with in-app purchases up to $59.99, and Apple Health Cycle Tracking costs nothing.
Which of these handles perimenopause?
Flo's listing describes a Perimenopause Score and a Menopause Timeline, and Apple Health lets you track menopause stages. Natural Cycles' listing describes NC° Perimenopause, which uses temperature to track hormonal changes and symptoms until post-menopause.
References
- U.S. Food and Drug Administration. De Novo database entry DEN170052, Natural Cycles, decision date 08/10/2018. accessdata.fda.gov. Fetched October 16, 2026.
- NaturalCycles Nordic AB. Natural Cycles, App Store listing (Monthly $21.99, Annual $149.99, supported devices, free NC° Band). apps.apple.com. Fetched October 16, 2026.
- Flo Health UK Limited. Flo Cycle & Period Tracker, App Store listing (in-app purchases, Premium, Pregnancy Mode, Perimenopause Score, Anonymous Mode, 2M ratings). apps.apple.com. Fetched October 16, 2026.
- Apple Support. Track your menstrual cycle in Health on iPhone (Cycle Tracking). support.apple.com. Fetched October 16, 2026.
- Federal Trade Commission. FTC Finalizes Order with Flo Health, June 22, 2021. ftc.gov.
- U.S. Food and Drug Administration. De Novo decision summary DEN170052 (Pearl Index 6.5 typical use, 1 perfect use). accessdata.fda.gov.
- U.S. Food and Drug Administration. 510(k) K202897, Oura temperature input for Natural Cycles (2021). accessdata.fda.gov.
- U.S. Food and Drug Administration. 510(k) K231274, Apple Watch temperature input for Natural Cycles (2023). accessdata.fda.gov.
- Natural Cycles. Devices (supported wearables, subscriptions, one device at a time). naturalcycles.com/devices. Fetched October 16, 2026.
Facts checked against official pages and named sources on October 16, 2026. Prices and policies change, so confirm current terms on each company's site before buying or subscribing.
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