Best Period Tracker Apps Compared

The short version: there is no single best period tracker app, there is the one that matches what you need it to do, whether that is basic cycle prediction, symptom logging for a GP conversation, or fertility planning. Flo, Clue, and Natural Cycles sit at the top for different reasons, and the privacy conversation around these apps matters more than most comparison posts admit.

Why this comparison needed writing

I run a business built on data and marketing, and I spend a stupid amount of time telling clients to read the fine print on any app before they hand over personal information. Period tracking apps are exactly the kind of tool where people skip that step because the app feels personal and low-stakes. It is not low-stakes. You are logging health data, sometimes sexual activity, sometimes mood and medication, and that data has to live somewhere.

I am not a doctor and this is not medical advice. If you have concerns about your cycle, pain, irregular bleeding or anything else, speak to your GP. What I can help with is the practical side: which app does what, what it costs, what it does with your data, and how to pick one without wasting a month trialling five different apps you will delete anyway.

The main contenders, side by side

Flo

Flo has around 380 million users worldwide according to the company's own figures, which makes it the most downloaded period tracker. It is free with a premium tier (roughly £8.99 a month or £49.99 a year as of 2026 UK pricing) that opens up symptom insights, an anonymous mode, and a chat feature with health assistants. The free version covers prediction, logging, and basic educational content, which is enough for most people who just want to know when the next period is coming.

Flo had a well-documented 2021 FTC settlement in the US over sharing health data with third parties like Facebook and Google, which it denied intentionally doing but settled anyway. It has since introduced an anonymous mode that strips your data from your identity. Worth knowing before you sign up with your real email and full name.

Clue

Clue is based in Berlin and markets itself heavily on being science-backed and GDPR-compliant, which matters if you are in the UK or EU and care about where your data physically sits. The free tier covers cycle tracking, symptom logging, and predictions. Clue Plus runs about £39.99 a year and adds longer-range forecasts and more detailed pattern analysis. Clue does not sell data to advertisers, which it states clearly in its privacy policy, and that single fact is why a lot of privacy-conscious users switched to it after the Flo controversy.

Natural Cycles

This one is different from the other two because it is cleared by the US FDA and UK-certified as a method of contraception when used correctly alongside a basal thermometer, not just period prediction. It costs around £84.99 a year including a compatible thermometer in the starter kit. This is the app for someone actively using cycle data to avoid or plan pregnancy, not someone who just wants a reminder that their period is due on Thursday. Typical use failure rate sits around 6 to 7 percent per published clinical data, which is why it comes with the thermometer requirement and a stricter daily logging habit than Flo or Clue.

Period Tracker by GP Apps and the NHS-adjacent options

There are smaller, less flashy apps built specifically for logging symptoms to bring to a doctor's appointment, with less emphasis on prediction algorithms and more on exportable PDF reports. If your main reason for tracking is to show a GP a pattern of heavy bleeding, pain, or irregular cycles, one of these simpler apps with a clean export function will serve you better than Flo's AI chat feature, which is built for engagement, not clinical handover.

A worked example: picking the right one for three different people

Say you run a small team of five women in an office and someone asks what app to use. Person A wants a simple reminder before a period starts so she can plan around it, no bells and whistles. Clue's free tier does this in under two minutes of setup. Person B is trying to conceive and wants data-backed fertility windows. Natural Cycles with the thermometer is the only option on this list with regulatory clearance for that specific use. Person C has been having irregular, heavy periods for four months and her GP has asked her to track symptoms for six weeks before the next appointment. A simpler logging app with a clean export beats Flo's conversational AI features here, because what the GP wants is a dated list of symptoms, not a chatbot summary.

Three different needs, three different right answers. Anyone who tells you there is one best app for everyone is selling you something or hasn't used more than one of these.

The uncomfortable bit nobody in this niche wants to say out loud

Most period tracker apps make money either through subscriptions or through data partnerships, and the free ones that look generous are often generous because your anonymised (allegedly) data is valuable to advertisers, insurers, and researchers. The 2022 US Supreme Court decision overturning Roe v Wade triggered a wave of articles telling women to delete their period apps entirely, and while that was a specific legal context tied to US state law, the underlying point stands everywhere: data you hand to a free app lives on a server you do not control, under terms you probably did not read. If you want to use one of these apps, read the privacy policy section on third-party sharing specifically, not the whole thing, just that section, and decide if you're comfortable. It takes four minutes.

This is the same advice I give anyone adopting any productivity tool for business or personal use: the convenience is real, but so is the trade-off, and most people skip the trade-off conversation entirely because reading privacy policies is boring.

Features worth comparing, not just listing

• Prediction accuracy: all three major apps use algorithms that improve with more logged cycles, typically needing three to four months of consistent input before predictions tighten up.
• Data export: Clue and the GP-focused apps make this straightforward with a PDF or CSV. Flo's export sits behind the premium tier.
• Partner sharing: Flo has a partner-linked mode so a partner can see cycle phase and mood logs, which some couples find useful and others find invasive. Worth discussing before switching it on.
• Symptom depth: Clue tracks over 30 symptom categories on the free tier, more granular than most competitors at that price point.
• Offline use: most of these apps require an internet connection for sync, which matters if you're logging on a work trip with patchy signal.

How to choose without wasting a month

Download two apps, not five. Log for one full cycle in both simultaneously. Compare which one's interface you open without being nagged by a notification, because the best app is the one you use consistently, not the one with the most features on a comparison chart. Delete the one you didn't open. This is the same approach I'd recommend for choosing between any two competing tools, whether that's a CRM or a SaaS platform for a business process: trial narrowly, decide on actual use, not on the sales page.

If tracking symptoms for a medical conversation is your main goal, print or export your log before the appointment rather than handing your phone to a GP mid-consultation. It saves time and means you don't have to explain how the app's interface works while you're also trying to explain your symptoms.

Where this fits into the bigger habit-tracking picture

Period tracking sits in the same category as any self-monitoring habit, similar in spirit to checking analytics on your own content or tracking who's engaging with your Instagram stories: useful data only if you look at it and act on patterns, otherwise it's just another app icon you ignore. Set a monthly ten-minute slot to review what you've logged rather than letting it sit there unread.

Frequently asked questions

Which period tracker app is the most private?

Clue is generally considered the most privacy-conscious mainstream option because it is GDPR-compliant by design, based in Germany, and states clearly in its policy that it does not sell data to advertisers. No app is perfectly private, so read the third-party data section of any app's policy before committing.

Is Natural Cycles accurate enough to replace contraception?

Natural Cycles is FDA-cleared and UK-certified as a contraceptive method when used correctly with the required basal thermometer, with a typical use failure rate around 6 to 7 percent in published data. Speak to your GP before relying on any app as your primary method of contraception, since correct daily use is essential to the stated accuracy.

Do I need a premium subscription to track my period ?

No. The free tiers of Flo and Clue both cover prediction, basic symptom logging, and cycle history, which is enough for most people who just want to know when a period is likely to start. Premium tiers mostly add longer forecasts, deeper insights, and export features.

Can I use a period tracker app to bring data to a GP appointment?

Yes, and it's one of the most useful ways to use these apps. Choose one with a clean export or PDF function, log consistently for the weeks your GP asks for, and bring a printed or exported summary rather than handing over your phone during the appointment.