Period Tracker for Teens: 8 Apps Compared on Safety (2026)
Teen cycles are supposed to be irregular for a few years, which changes what a tracker is for. Here is what to pick, and what to skip.
A period tracker for teens has a different job than one for adults, because teen cycles are supposed to be irregular. The American College of Obstetricians and Gynecologists says cycles are often irregular during adolescence, that 90% of them fall anywhere between 21 and 45 days in the early years, and that it takes until about the third year for most cycles to settle into the adult range.
So the best tracker for a teenager is not the one with the cleverest predictions, which will miss anyway; it is the one that keeps an honest record, respects a minor’s privacy, and does not need a credit card.
This guide compares eight options on exactly those three things, three apps built for teens and five general ones, whether you are the teen choosing or the parent helping, and ends with the signs doctors say are worth a visit.
What a period tracker for teens needs to get right
Start with what teen cycles actually look like, because it changes what you should expect from any app. ACOG’s guidance on menstruation in girls and adolescents, endorsed by the American Academy of Pediatrics, puts the median age of a first period between 12 and 13, says cycles are often irregular during adolescence and may run somewhat long in the early years, and gives the range: 90% of cycles fall between 21 and 45 days.
By the third year after a first period, 60 to 80% of cycles are 21 to 34 days long, which is the adult pattern. The Office on Women’s Health says the same thing more simply: for a few years after your first period, cycles longer than 38 days are common.
That is why predictions miss. The Apple Women’s Health Study measured cycle-to-cycle variability across 165,668 cycles and found it 46% higher in participants under 20 than in the steadiest age group. An app predicting from three logged periods is guessing against that spread, and the research on how accurate period tracker apps are shows even adult cycles defeat calendar predictions for ovulation.
What a teen tracker can do well is the thing ACOG actually asks for: it recommends clinicians treat the menstrual cycle as a vital sign and notes that asking a patient to chart her menses is beneficial when her history is vague. A dated record of period starts, lengths, and flow is the most useful thing a teenager can bring to a doctor, and every app below can produce one.
Best period tracker for teens: 8 options compared
Three rules of thumb fall out of that table. For a tween or a younger teen, Oky is rated 9+ and Apple Health has no age gate at all. For a teen who wants an app made for her, Luna is built around early cycles and carries no ads. For an older teen who wants a fuller app, Clue’s parent-permission step is a feature, not a hurdle, because it puts the privacy settings in front of both of you at setup.
Luna: the period tracker built for teens by a teacher
Luna says it was created by a middle school teacher who wanted something genuinely helpful for their students, and the design follows from that: prep-day reminders before a period, short lessons and a question box with sourced answers, and a calendar a teen can decorate. Its site makes three promises in plain words: no ads, ever, your data is never sold, and an optional passcode lock.
A parent or guardian can link an account to see when the next period is likely and have supplies ready, and Luna states the teen’s private notes are never shared with them. Its App Store listing is rated 13+, free to download, with a Luna+ subscription at $3.99 a month or $19.99 a year that backs up the data. Mozilla did not test it, so there is no independent privacy score to quote.
Oky: the free one from UNICEF, rated 9+
Oky describes itself as the world’s first period tracker app for girls, created with girls, and it delivers information about menstruation in fun, creative and positive ways across more than a dozen languages. It is published by UNICEF, and its App Store listing is rated 9+, filed under Education, and free with no in-app purchases.
That 9+ rating makes it the only app here a parent can point an 11 or 12-year-old to without working around an age rule. Its self-reported privacy label lists analytics data not linked to identity, and Mozilla did not test it.
we are luna: the big-sister app, with a label to read first
The UK app we are luna, a different app from the Luna above, pairs a period tracker with anonymous questions answered by its medical team, and says its content is reviewed by medical professionals and safeguarding experts. It leaves out adult features like fertility tracking. Its own guide says it is recommended for ages 11 to 18 in most countries and available to teens aged 13 and over in the United States, with a parent setting up the account for anyone below the age of consent.
The thing to read before installing is the privacy label on its App Store listing, which the developer reports itself: it lists usage data under “Data Used to Track You”, meaning data that may be used to track across other companies’ apps and websites. The app is free with a Premium tier at $4.99 a month or $39.99 a year, and a parent can hold a linked account while the teen’s reading, tracking and questions stay private.
Two more names you will meet in search results. MagicGirl lists a chat with other app users among its features, which is the thing a parent should look at before a younger teen installs it. Teena, from the makers of the Daysy thermometer, is a free puberty guide and period tracker rated 4+, the lowest rating of any app mentioned here; its listing was last updated in 2023, so check that it still runs well before building a habit around it.
Apple Health: the period tracker app for teens already on the phone
If the teen has an iPhone, the tracker is already installed. Per Apple’s own guide, Cycle Tracking in the Health app logs periods and symptoms, turns on predictions and notifications, and can flag irregular cycles, infrequent periods, prolonged periods, or persistent spotting from the previous six months of data, which is close to the list a pediatrician would check.
There is no account to create and no company to trust beyond Apple. Apple’s separate guide covers sharing Health data with someone you trust, which is the cleanest way for a parent to see the record without holding the log themselves.
Euki: the private one
Euki is rated 13+ on the App Store and describes itself as the period tracker that doesn’t track you: no account, email, or phone number, data stored only on the device, a PIN lock, free, and run by a nonprofit, open-source project. Mozilla’s test confirmed the design and gave it the set’s only 10/10.
Two things to know before handing it to a younger teen: it has no backup, so a lost phone is a lost log, and it includes information on sexual health, STIs, and reproductive healthcare alongside the tracker. For many families that is a plus; either way, it is worth knowing.
Clue: the one with a parent step built in
Clue’s own support page says the app is available to young people to help them navigate their first years of getting periods, and lays out the rules: on first use you confirm whether you are 16, and if not, you need a parent or guardian’s permission to use the app and their help to set up your privacy settings. In the United States, under-13s cannot use Clue at all.
Mozilla scored it 8/10 for handling each data-sharing purpose as a separate, editable choice, with the caveat that ad-related sharing is opt-out. The setup conversation Clue requires is the moment to switch that off. If the choice comes down to the two biggest apps, the Flo vs Clue comparison covers the rest.
Flo: the biggest app, with age rules to check
Flo is rated 13+ on the App Store, and Flo’s help center sets its own floor: you should be at least 13 to use Flo, 16 for EU residents, and some functions may be limited for users younger than 18. Mozilla scored it 7/10 and noted that sharing basic app and device data with ad and analytics partners is an optional consent whose off switch worked in testing.
Flo is the broadest app here, closer to a health diary than a calendar, which is a good fit for an older teen who wants the articles and a less obvious fit for a 13-year-old who wants a record.
Stardust: popular, social, and the one to think twice about
Stardust is rated 13+, built around astrology-flavored cycle tracking, comparison with friends, and a partner mode, and it is genuinely popular with younger users. The reason it sits last is not ours: Mozilla scored it 2/10 after observing data sent to third-party tracking services from the moment the app opened, later including birthdate, birth control type, reproductive goals, and specific symptoms, and found no in-app settings to fully disable it.
For an adult that is a trade-off to weigh. For a minor’s reproductive health data, it is the finding to lead with.
Period tracker for tweens: what works under 13
A period tracker for tweens has fewer honest options than the app stores suggest, because almost every app is rated 13+ and Clue and Flo both set 13 as their own minimum in the United States. Under 13, the choices that fit the rules are Oky, which is rated 9+, Teena, which is rated 4+, Apple Health, which has no signup at all, and a paper calendar.
The paper option is not a consolation prize. ACOG’s guidance asks for a charted record of periods, not for an app, and a first period that arrives at 10 or 11 is inside the normal range it describes. The habit of marking day one transfers to any app later.
Period tracker for teenager or parent: who holds the record?
The teen does. Every option above works best when the person whose cycle it is logs it, and the parent’s role is to know the record exists and to see it when the teen chooses. Apple Health’s sharing feature, Luna’s optional parent link and Clue’s parent-permission step are built for exactly that split.
What does not work is a parent tracking a teenager’s cycle in their own app: the log goes stale, and the teen learns nothing about reading her own body. If you are the parent and the first period has not arrived yet, our guide to the signs your daughter is about to start her period covers the run-up and the kit; the tracker comes after.
A teenager’s cycle is allowed to be irregular for three years. The app’s job is to write it down, not to explain it away.
When the record shows something to ask a doctor about
This is the payoff of tracking. ACOG treats the cycle as a vital sign because a few patterns in the log deserve evaluation, and a dated record turns a vague “it’s been a while” into a clear answer.
For the adult definitions and how to count a cycle properly, our guide to what counts as an irregular period applies from the third year onward; before that, ACOG’s wider range is the one to use.
Where Otty stands
Otty is a period tracker built for couples, and its audience is adults. It is rated 13+ on the App Store and its terms set the same 13-and-over floor most apps use, but neither of those is a recommendation, and we would point a teenager to the list above rather than to us. If you are choosing an app for yourself as an adult and care about the privacy side, our comparison of six period trackers on privacy is the companion to this guide, and our best period tracker app guide compares ten trackers by the job each one does.
Period tracker for teens FAQ
The takeaway on a period tracker for teens: expect irregular cycles for up to three years, choose the app that keeps a record without asking for an account or leaking data, let the teen own the log, and bring the dated record to the doctor if any item on the checklist shows up.
