One Big Calendar: Period
Cycle Tracker & Daily Planner
Free · In‑App Purchases
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.
WHY IT'S DIFFERENT
Most calendars ignore your cycle. Most cycle apps ignore your calendar. OBC does both. Your Monday standup and your ovulation window are on the same grid. Your Friday deep-work block and your PMS forecast are on the same grid. Nothing to context-switch between.
WHAT'S ON YOUR GRID
- All your existing calendars (iCloud, Google, Outlook, Fastmail, work + personal)
- Your menstrual cycle: period days, phases (menstrual, follicular, ovulation, luteal), next-period prediction
- Cosmic overlays you can toggle: moon phases, planetary retrogrades with shadow windows, solstices and equinoxes, eclipses, zodiac seasons
- Symptoms, mood, intimacy, weight — one-tap logs
- Focus Today card: what your day looks like on this phase
PRIVATE
- Everything stays on your device or in your own iCloud
- No ads, no trackers, no data sold to anyone
- Optional Apple Health sync — two-way, so your existing period logs show up here and the ones you add here go back to Health
- Anonymous feedback only — we never see who you are
FOR PEOPLE WHO
- Live out of a calendar and are tired of guessing where in their cycle they are
- Want to plan travel, meetings, or deep work around their phases without a separate app
- Care about cosmic overlays (moon, retrograde, eclipses) but don't want a full astrology app
- Have ADHD and need one screen for everything, not five
NOT MEDICAL ADVICE
For planning and tracking only. Not a medical device, not a contraceptive, not a substitute for professional care. Consult a healthcare professional for medical decisions.
TERMS & PRIVACY
Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy: https://hellogoodday.com/onebigcalendar/privacy
Subscriptions auto-renew at the price shown unless cancelled at least 24 hours before the current period ends. Manage or cancel any time in Apple Account Settings.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
• Pro: Patterns is here. See every symptom lined up by cycle day, one row per cycle, and tap any symptom for when it usually shows up, how often, and in which phase.
• Predictions keep up when a period goes unlogged. Once it's due, it shows as expected any day. If it stays unlogged, the app estimates the next one for you. Log the real date, even an earlier one, and everything updates.
• Clearer first steps: Patterns and your cycle screen show what to log to get started.
• Fix: the welcome message no longer covers the tab bar.
The developer, Hello Good Day LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
- User Content
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Hello Good Day LLC
- Size
- 5.5 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 10 more
- English, Dutch, French, German, Italian, Japanese, Korean, Portuguese, Russian, Simplified Chinese, Spanish
- Age Rating
13+
- 13+
- Infrequent
Medical Treatment information
Sexual Content or Nudity
Contains
Health or Wellness Topics
- In-App Purchases
Yes
- Pro Lifetime $49.99
- Pro Yearly $19.99
- Pro Monthly $2.99
- Copyright
- © Hello Good Day LLC
