A calm, beautiful period & fertility tracker. Log your cycle, get clear predictions, and know your fertile window — private, and always on your device.
✿ Coming soon to iOS & AndroidThoughtfully designed for real life — accurate, calm, and respectful of your privacy.
Log your period in a tap and see your full history on a clean, colourful calendar.
Know when your next period is due, with predictions that learn from your recent cycles.
See your best days to try for a baby, with ovulation and fertile-window estimates.
PremiumTrack symptoms, mood, notes, and daily logs to spot your personal patterns.
Log basal body temperature and cervical mucus with clear, insightful charts.
PremiumSwitch to a week-by-week pregnancy view with your due date front and centre.
PremiumOptional local reminders for upcoming periods and your fertile window.
Data lives on your device first. Sync is optional, encrypted in transit, never sold or used for ads.
Core tracking is free forever. Upgrade any time for fertility insights and more.
The essentials, forever free
Everything, for those trying to conceive
A note on health & safety. BestDays is provided for informational and educational purposes only. Predictions are estimates based on the data you enter and may not be accurate for everyone. BestDays is not a form of contraception and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions about your health.
The essentials about how BestDays works and keeps your data private.
BestDays is a period, cycle, and fertility tracking app for iOS and Android. It lets you log your period, see predictions for your next period, and — with Premium — find your fertile window and best days to try to conceive.
Yes. Core tracking — period logging, calendar, next-period predictions, symptoms and mood, reminders, and multi-device sync — is free forever. An optional Premium subscription adds fertile-window and ovulation predictions, BBT and cervical-mucus charting, pregnancy mode, cycle insights, and data export.
BestDays Premium estimates your fertile window and ovulation from your logged cycle data, so you can identify your best days to try to conceive. These are estimates for informational purposes and are not a guarantee.
Yes. BestDays is offline-first: your data is stored on your device and predictions are computed on-device. Syncing is optional and encrypted in transit. We never sell your data and never use your health data for advertising.
Yes. BestDays works fully offline. Signing in and syncing is optional and only exists to back up your data and use it across multiple devices.
No. BestDays is not a contraceptive and is not a substitute for professional medical advice. It is for informational and educational purposes only. Always consult a qualified healthcare provider.
Join BestDays and take the guesswork out of your cycle — free to download.