The only calendar that also knows your body's week.
One Big Calendar puts your work and your cycle on a single screen. iCloud, Google, and Outlook events sit right next to your period, phases, moon, and symptoms — so you can see how your week and your body line up, and plan accordingly.
Your Monday standup and your ovulation window, side by side.
Most calendars ignore your cycle. Most cycle apps ignore your calendar. One Big Calendar does both — nothing to context-switch between.
- All calendarsiCloud, Google, Outlook, Fastmail, work + personal
- Same gridYour deep-work block and your PMS forecast together
- One screenFor everything, not five apps
What your day looks like on this phase.
The Focus Today card shows your day in context of where you are in your cycle, so you can plan travel, meetings, or deep work around your phases.
- Focus TodayYour day, read through your current phase
- One-tap logsSymptoms, mood, intimacy, weight
Period, phases, and what's next.
See period days, all four phases, and your next-period prediction right on your calendar. Optional Apple Health sync is two-way — existing period logs show up here, and the ones you add here go back to Health.
- PhasesMenstrual, follicular, ovulation, luteal
- PredictionNext-period forecast on the grid
- Apple HealthOptional, two-way sync
The sky on your schedule — toggle it on or off.
For people who care about the moon, retrogrades, and eclipses but don't want a full astrology app.
- MoonMoon phases on every day
- RetrogradesPlanetary retrogrades with shadow windows
- SeasonsSolstices, equinoxes, eclipses & zodiac seasons
Live out of a calendar.
Calendar-first
Tired of guessing where you are in your cycle.
Planners
Plan travel, meetings, or deep work around your phases without a separate app.
Sky-watchers
Moon, retrograde, and eclipse overlays without a full astrology app.
ADHD brains
One screen for everything, not five.
Your data stays yours.
Everything stays on your device or in your own iCloud. No ads, no trackers, no data sold to anyone — and feedback is anonymous, so we never see who you are.
- All your calendars on one grid
- Cycle phases & next-period prediction
- Moon, retrograde & eclipse overlays
- Optional Pro upgrade in the app
Questions, answered.
Which calendars does it work with?
All your existing calendars — iCloud, Google, Outlook, Fastmail, work and personal — show up on the same grid as your cycle.
Where is my data stored?
Everything stays on your device or in your own iCloud. There are no ads, no trackers, and no data sold to anyone.
Does it work with Apple Health?
Yes, optionally. The sync is two-way: your existing period logs show up in One Big Calendar, and the ones you add go back to Health.
How much does it cost?
One Big Calendar is free to download, with an optional Pro upgrade available in the app. Subscriptions auto-renew at the price shown unless cancelled at least 24 hours before the current period ends, and you can manage or cancel any time in Apple Account Settings.
Is it medical advice or birth control?
No. It's for planning and tracking only — not a medical device, not a contraceptive, and not a substitute for professional care. Consult a healthcare professional for medical decisions.
What is One Big Calendar, who is it for, and what does it run on?
One Big Calendar puts your calendar events and your menstrual cycle on one screen. It is for people who live out of a calendar and want to plan around their phases without a separate app, and it runs on iPhone and iPad. Connect your calendars, then log your period days and symptoms on the same grid.
See your period and your work calendar on one screen · Free printable blank calendar
Your week and your body, finally on one screen.
See how your schedule and your cycle line up — and plan accordingly.
For planning and tracking only. Not a medical device, not a contraceptive, not a substitute for professional care.