How we count
Settings → About → How we count. Every number the app shows comes from one of the rules below, and the screen that shows a number links back here. The screen opens with Your numbers — your own cycles, shortest and longest, and today's cycle day — and then explains every rule behind them. The switches themselves live elsewhere: the medicine-started-bleed one in Settings → What you see → Sections, cards and counting → Counting, the forecast in Settings → What you see → Show next period range, and the guideline band on the Cycle lengths screen itself — Trends → Cycle lengths → Details.
A cycle
From the first day of one period to the day before the next. A cycle is completed when the next period has started; one still running is not counted, however long it has lasted.
Your range
The shortest and longest of your completed cycles, and the middle one. Cycles left out: those interrupted by a state (hormonal contraception, pregnancy, breastfeeding, no periods) and those you marked Not typical.
A period day
Every day from Started to Ended, inclusive. Days in between need no marking. Spotting outside a period is not a period day and starts no cycle — unless you say it was the start.
Logged days, and why counts look small
A symptom count reads “21 of 69 logged days”. The 69 is the number of days you said anything about symptoms — by rating one, or by tapping Nothing today. Days you skipped are named separately and never counted as “no”.
Your choice: periods brought on by a medicine
Whether a bleed you labelled Started by a medicine begins a cycle. The app asks the first time it matters and keeps your answer; change it later in Settings → What you see → Sections, cards and counting → Counting, with the switch “Periods started by a medicine begin a new cycle”. See periods brought on by a medicine.
Your choice: cycles that were not typical
Any cycle can be marked Not typical, with a reason. It stays in your calendar and your list, and drops out of the range and the middle value.
The forecast
Off unless you switch it on. A range built from your own recent cycles — never a date, never a countdown — and it disappears once you pass the longest of your last six cycles.
The guideline band
Off unless you switch it on. A band on the cycle-length chart showing what the 2023 international guideline describes, drawn behind your bars, with the recommendation number. The app never places you against it.