period tools

Free Period Tracker

Tap the days you’re on your period and this tracker learns your rhythm — predicting your next period, fertile window, and ovulation day right on the calendar. It runs entirely in your browser: no account, no sign-up, and nothing about your cycle ever leaves this device. It’s the same accurate cycle math behind our calculators, turned into a simple log you can keep coming back to.

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How the free tracker works

Most period apps make you create an account before you can log a single day — and then quietly build a profile from the data you give them. This tracker takes the opposite approach. Everything happens on your device. You tap the calendar days you’re bleeding, and that’s it; the prediction math runs locally and instantly.

Under the hood it uses the same logic as our Period Calculator. The first day of each run of period days becomes a cycle start. With two or more starts, it measures the gaps between them to find your personal average cycle length and whether your cycles are regular (varying by a week or less) or irregular. It then projects your next six cycles, placing the predicted period, fertile window, and ovulation day onto the calendar.

Ovulation is estimated as roughly 14 days before your next expected period — the luteal phase is the most stable part of the cycle — and the fertile window covers the five days before ovulation plus ovulation day, reflecting how long sperm and egg stay viable. These are estimates, not lab results, and they get sharper the more cycles you log.

Why tracking your cycle helps

Knowing your pattern makes a surprising number of things easier: planning trips and events around your period, understanding mood and energy shifts across the month, spotting when a period is genuinely late versus just a normal few days’ drift, and having real dates to share if you ever see a doctor about your cycle. A tracked history turns “I think it was a few weeks ago” into an exact answer.

  • See at a glance how many days until your next period
  • Learn your personal average instead of relying on the textbook 28 days
  • Notice irregular cycles early and bring the data to an appointment
  • Plan around your fertile window, whether you’re trying or simply curious

Your privacy is the point

Your cycle is some of the most personal data there is, and we think it should stay yours. This tracker stores everything in your browser’s local storage and never transmits it. There’s no account to hack, no profile to sell, and no third party in the loop. If you clear your browser data the log is gone — that’s the trade-off for keeping it fully private and device-only. When you want your history backed up and synced across your phone and laptop, ad-free, Period Tools Pro does that with the same privacy promise — your data encrypted and never sold.

Frequently asked questions

Is this period tracker really free?
Yes, completely. There is no account, no sign-up, and no paywall. You tap the days you are menstruating and the tracker calculates your next period, fertile window, and ovulation day for free. The optional Period Tools Pro upgrade only adds ad-free browsing and cross-device sync — the tracking itself is always free.
Where is my cycle data stored?
Only on the device you are using, in your browser's local storage. Nothing is uploaded to a server, saved to our database, or shared with anyone — we never see it. Because it lives on this device, clearing your browser data or switching phones will remove it. If you want your log to follow you between devices, that is exactly what the Pro sync option is for.
How many periods do I need to log for accurate predictions?
One logged period is enough to start predicting, using a typical 28-day cycle. After two or more period starts, the tracker calculates your personal average cycle length and flags whether your cycles are regular or irregular. Three to six cycles gives the most reliable personal pattern.
What do the colours on the calendar mean?
Solid rose days are periods you have logged. Light rose days are your predicted upcoming period. Light purple days are your estimated fertile window, and the darker purple day with a dot is your estimated ovulation day. Today is outlined with a ring.
Can I use this tracker to avoid or plan a pregnancy?
It is a helpful planning and awareness tool, but it is not a contraceptive method and should not be relied on to prevent pregnancy. Fertile-window and ovulation estimates are based on cycle averages and can shift with stress, illness, and other factors. For contraception or conception decisions, talk with a healthcare provider.

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