Predict your next period, fertile window, and ovulation day. All data stays on your device — nothing is uploaded or shared.
🔒 Your data is saved only in your browser (localStorage). Nothing leaves your device.
Know when to expect your period up to 6 months in advance — pack accordingly, schedule events, and never be caught off guard.
Whether you're trying to conceive or just want to understand your body, your fertile window is marked clearly on the calendar.
No app to install, no account to create, no health data sent to any server. Everything stays in your browser — period.
The fertile window is the days you can get pregnant in a given cycle. Sperm can live up to 5 days in the reproductive tract, and the egg survives ~24 hours after ovulation. So the fertile window is roughly 5 days before ovulation through 1 day after — typically days 10–15 of a 28-day cycle.
If your cycle varies by more than 5–7 days each month, predictions will be less accurate. Log several periods over time so the tracker can use your actual average. For very irregular cycles, consult a healthcare provider.
No. This tracker is for informational purposes only. The fertility awareness method (FAM) as contraception requires specific training and is most effective when combined with other monitoring. Always use proven contraceptive methods if you wish to avoid pregnancy.
Your logged period history is stored in localStorage. Clearing browser data, using private/incognito mode, or switching devices will erase your history. Consider noting your dates elsewhere for backup.