How this works
- Pick your goal: tracking your cycle, planning a pregnancy or avoiding one.
- The calendar shows possible ovulation and fertile days next to your period forecast.
- Log ovulation tests or connect Apple Health to refine the day.
How does HeySis work out ovulation?
From your cycle average, or from a sign you logged, like a positive ovulation test. Basal temperature and LH tests from Apple Health refine the day. If your cycle lengths vary a lot, the calendar skips ovulation and phases and still shows your period forecast. On hormonal birth control or while breastfeeding, it doesn't mark ovulation at all.
Can I use it to avoid pregnancy?
No. Ovulation shifts from cycle to cycle, and some cycles have none at all, so a calendar can't find safe days. If you don't want to get pregnant, use contraception whatever the date. If you turn on those reminders with the goal set to avoiding pregnancy, they say the same.
The ovulation calendar, fertile days and reminders are free.
Common questions
How long is the fertile window?
Usually about six days. Sperm usually live up to five days, sometimes up to seven, so the window opens before ovulation, and the likeliest days are the ones closest to it.
Do I need ovulation tests?
They help if you want more than a calendar guess: a test shows when ovulation is close. Log the result in HeySis, and the forecast adjusts to your body.
Can my partner see my fertile days?
Only someone you add to your Circle as a partner can see an estimate of it; friends can't.
