A cycle tracker that expects your cycles to vary
Standard period apps predict the next date from the last one and are wrong constantly when cycles run 30, 41, then 33 days. This one records what happened, shows it plainly, and only offers an estimate once there is enough data to justify one.
How a cycle is counted
A cycle starts on a bleeding day (light, medium or heavy) whose previous day was not a bleeding day. Spotting does not start a cycle. The length of a cycle is the number of days until the next one starts.
During setup you enter when your last period began, so there is a starting point on day one. If your logged days already show a period start within three days of that date, the app uses your logged days instead of counting it twice.
For each cycle the app also counts bleeding days, so you can see period length next to cycle length.
Cycle history, with the outliers marked
Trends shows each cycle: start date, length, and bleeding days. A cycle shorter than 21 or longer than 35 days is flagged, because those are the usual limits clinicians use when talking about regular cycles. Being flagged is information, not a warning.
The chart on the right uses the same lengths as the screenshot: 31, 29, 38, 33, 41 and 30 days. Bars outside the dashed 21 and 35 day lines are marked in pink.
When you will see a prediction
- Under 3 completed cycles. No prediction. The screen says “Estimates appear after 3 logged cycles.” A guess from one or two cycles would mostly be noise.
- 3 or more completed cycles. The app averages your most recent cycles (up to six) and shows a date labelled “Estimate”. It also reminds you that your cycles can vary.
- A cycle runs long. Once the current cycle passes 35 days, the late period check takes over. It is a separate page of this site.
What else it touches
Cycle day on Home
Home shows today’s cycle day once a cycle start is known.
No fertile-window claims
It does not predict ovulation or fertile days. With irregular cycles, date-based ovulation predictions are unreliable, so the app does not make them.
Unlimited history
Cycle history is not limited by plan. Premium does not gate it.
Feeds the doctor report
Cycle lengths and the count outside 21 to 35 days appear in the report and in the PDF table.
It does not diagnose PCOS, call a cycle abnormal or tell you what to do about one. Cycle length alone does not diagnose anything. If your cycles worry you, the report is there to make that conversation easier.
Questions
What counts as a regular cycle here?
21 to 35 days. Anything outside that is marked. The thresholds are fixed, not personalised.
Why is there no prediction yet?
Predictions appear after three completed cycles. A completed cycle needs two logged period starts, so log your period days as they happen.
Does spotting count as a period?
It is recorded, but it does not start a cycle. Light, medium and heavy flow do.
Can I add periods from before I installed the app?
You can set when your last period started during setup. After that the log records each day as you go, so history builds from the day you start.
The screenshots on this page are from the real app, filled with sample entries made for this page. They are not anyone’s health data. Not a medical device. Updated October 7, 2026.