Most period apps are built around a 28-day cycle and treat anything else as an error. With PCOS, long and unpredictable cycles are common, and they vary from one to the next. Ovessa is built around one rule: never pretend to know a day it can’t know.
The rules behind every prediction
Five rules are enforced in the app’s code and covered by its tests:
- No prediction before three cycles. Ovessa waits until it has seen at least three of your period starts.
- A window, never a day. The likely window can never shrink below four days.
- More variation, wider window. If your cycles vary a lot, the window widens instead of faking confidence.
- Always worked out fresh. Predictions are calculated from your logs each time and never stored, so a correction to an old period changes them at once.
- The calendar matches the card. The days drawn dashed on the calendar are exactly the window the card states.
What you see, and when
The Cycle tab’s month calendar marks your period days (stronger colour for heavier flow), logged symptoms, today, and the likely window as a dashed outline on future days only. A legend under it lists only the marks actually on screen.
Under the calendar, the card depends on how much Ovessa knows:
- Three or more cycles: Next period · likely with a date range and a bar that shows where in the window it’s most likely. The card says it plainly: “A wide window is normal with PCOS. We won’t pretend to know the exact day — the range narrows as you log more cycles.”
- Fewer: a factual This cycle · Day N, or calm progress toward three cycles.
On Today, the cycle card counts from your last logged period against how long your cycles usually run. When this cycle runs past your usual length, it says so: “Your cycle tends to run long — this is normal for you, not a missed period.”
Your cycles
Your cycles shows your average cycle length with its real shortest and longest, your average period length, how many cycles are tracked, and a timeline of every cycle to scale. Numbers Ovessa can’t know yet read “—” rather than a guess. With two or more complete cycles it says the useful thing out loud: your cycles vary by about N days, which is typical with PCOS, so Ovessa tracks the range instead of pretending it’s fixed.
Getting better predictions
- Log period starts as they happen, or backdate them from the calendar.
- Bring in your history. If your cycle history is already in Apple Health from another app, connecting Apple Health brings it into Ovessa, so you don’t wait months for three cycles. See Apple Health with Ovessa.
- Don’t chase a narrow window. With PCOS a wide window is honest, not broken.
What predictions are not
Ovessa’s cycle windows are statistical estimates over your own history. They are not contraception and must not be used to plan or avoid a pregnancy. Ovessa is not a fertility tool and makes no fertility claims. For anything medical, talk to your doctor, and bring the Summary or the doctor report.
Download on the App Store (opens the App Store in a new tab)