For a dedicated iPhone app, we’d pick Plum. We make it, so check our reasons against the rest of this page. It’s simple to log, it has no ads, it never asks to track you, and its period, fertile window and ovulation predictions come with the app at no cost. Your history is backed up, so a new phone picks up where the old one stopped. If you don’t want another app, Apple’s Cycle Tracking is already in Health. Pick Euki if nothing should leave your phone, and Clue or Flo if you want a big content library or you also use Android.
How we chose
We make Plum, and it’s on this list. There are no affiliate links, and nobody paid to be here. We read each company’s own pages and its US App Store listing on October 12, 2026, and every claim about another app links to one of those sources below. Where a source was silent, we say “not stated” rather than guess.
We asked each app the same things. Is it at home on an iPhone? What do you get without paying? Where does your data live? What does Apple’s privacy label list under Data Used to Track You? And what is it clearly best at? We left prices out, because they change by country and by month.
Plum, for a simple tracker with no ads and a backup
Plum is made by Sticky Rice Labs and runs only on iPhone. Logging a day takes a tap or two. You can track 27 things in four groups, including flow, pain, mood, energy, sleep, cravings, discharge, sex, exercise, the pill, and ovulation and pregnancy tests. It predicts your next period, fertile window and ovulation, and the forecast adjusts as you log. Reminders arrive three days before your period and the day before at 7 pm, then at 9 am on the day. There’s an ovulation heads-up the evening before, too.
Logging, the calendar, all three predictions, reminders, birth control tracking and private groups come with the app at no cost. Plum Premium, a monthly or yearly subscription, adds insights and the full set of more than 50 phase tips. Without it you still get one full tip a day. There are no ads. Plum never sells your data or uses it for advertising, and since it never asks to track you, its App Store listing has no Data Used to Track You section.
You sign in with Apple or Google. Your data is stored encrypted on Plum’s servers with a copy on your phone, so it isn’t on-device only, and you can delete your account and data inside the app. Coming from Clue? Plum can import your history. Friends can also see each other’s period days in a private group, while symptoms and moods stay private. Know the gaps before you install. Plum has no Apple Watch app, no widget, no iPad layout and no Apple Health sync, and there’s no free-text notes box.
Apple Cycle Tracking, for the tracker already on your phone
Cycle Tracking sits inside the Health app, so there’s nothing to install or sign up for. Apple’s guide says you can log period days, flow, symptoms, spotting and basal body temperature, and you can log from an Apple Watch. It predicts your next period and fertile window and can notify you before each. It also flags a possible cycle deviation and exports your history as a PDF. With an Apple Watch Series 8 or later, or any Ultra, it estimates the day you likely ovulated after the fact. Our Apple Watch period tracker guide says what each model can do.
Apple says Health data synced to iCloud is end-to-end encrypted when two-factor authentication is on, so Apple can’t read it. The guide describes logging, predictions, notifications and history, and says nothing about articles or tips.
Euki, for keeping everything on the phone
Euki is free and open source, and a US nonprofit runs it. Its site says there are no paywalls. What you log stays on your phone with no account, and you can set a PIN that isn’t tied to your email or number. You can also schedule sweeps that delete your data. It predicts your next period after two months of tracking, and it can remind you about appointments and medication. Its FAQ is frank about the cost. Lose your phone and the history goes with it, and fertility tracking is limited to custom notes for now. It’s on iPhone and Android, in English and Spanish.
Clue, for science content and Android
Clue, from Biowink GmbH, runs on iPhone and Android. The free version gives you an account, essential cycle statistics and basic predictions. Its Clue Plus subscription adds predictions up to 12 months ahead, Clue Connect sharing, extra analysis, the full content tab and modes for trying to conceive, pregnancy and perimenopause. Apple Watch integration is a Clue Plus feature too. Clue’s privacy policy says its data is stored on servers in the European Union, and its home page says it has never sold your health data and never will. Its App Store label lists Identifiers under Data Used to Track You.
Flo, for the most features in one app
Flo says over 420 million people use it to track periods, ovulation, pregnancy and perimenopause. It’s on iPhone and Android, and its App Store listing says it works with Apple Watch. Flo’s own comparison table puts period and ovulation predictions, symptom tracking, the calendar, cycle history, Secret Chats and Anonymous Mode in the free version. The health library, Health Assistant, Symptom Checker, cycle trends, a doctor’s report and Flo for Partners need Flo Premium. Its App Store label lists Purchases, Location, Identifiers and Usage Data under Data Used to Track You.
Natural Cycles, for birth control
No period tracker here is contraception, and that includes Plum. Natural Cycles is the exception worth knowing about. Its home page calls it the only FDA-cleared birth control app and gives its own figures of 93% effective with typical use and 98% when used as intended. It works from your temperature and other body signals, measured overnight with its own band or a compatible wearable. It’s built and regulated for that job, so it isn’t a straight swap for a period diary.
Side by side
| Runs on | Included at no cost | Where your data lives | Data Used to Track You | Apple Watch | |
|---|---|---|---|---|---|
| Plum | iPhone | Logging, calendar, period, fertile window and ovulation predictions, reminders, birth control, groups | Plum’s servers, encrypted, with a copy on the phone | No section | No |
| Apple Cycle Tracking | iPhone, Apple Watch | Everything, built into Health | The phone, with end-to-end encrypted iCloud sync when two-factor is on | Built in, no listing | Yes |
| Euki | iPhone, Android | Everything, with no paywalls | The phone only | Data Not Collected | Not stated |
| Clue | iPhone, Android | Account, essential statistics, basic predictions | Servers in the European Union | Identifiers | With Clue Plus |
| Flo | iPhone, Android | Period and ovulation predictions, symptoms, calendar, history, Anonymous Mode | Not stated on the pages we read | Purchases, Location, Identifiers, Usage Data | Yes |
What to look for in an iPhone period tracker
- Read the App Store label before you install. The Data Used to Track You section is Apple’s summary of what goes to other companies for advertising.
- Decide if you want a backup. An on-device app is the most private choice, and a lost phone takes your history with it.
- Check what predictions cost. Some apps keep the fertile window or longer forecasts for subscribers.
- List the iPhone extras you need. If you want Apple Watch logging, a widget or Health sync, check for each one. Plum has none of the three.
- Look for a forecast that admits doubt. Our guide to how Plum’s predictions work shows what a range and “still learning” mean in practice.
For a wider look beyond iPhone, see our best period tracker apps roundup.
Sources
- Plum Period Tracker & Diary on the App Store
- Apple, Log menstrual cycle information in Health on iPhone
- Apple, View menstrual cycle predictions and history in Health on iPhone
- Euki home page, Euki app features and Euki FAQs
- Euki on the App Store
- Clue home page, What’s included in Clue Plus and Clue privacy policy
- Clue on the App Store
- Flo home page and Flo Premium
- Flo on the App Store
- Natural Cycles home page
