Calendar 366 vs Calendars by Readdle
Price, platforms and features side by side. The table says where each price was read and when.
Calendar 366
Calendar and task app for iPhone, iPad, Apple Watch and Mac
Calendars by Readdle
Calendar and task planner for iPhone, iPad, Mac and Apple Watch
Where they differ
- Calendar 366 starts at $19.99 per year for Pro on the App Store. Calendars by Readdle starts at $19.99 per year, or $3.99 per month (US App Store in-app purchases).
- Calendar 366 can be bought with a one-time purchase.
- Calendar 366 also covers menu bar app.
- Calendars by Readdle also covers habit tracking.
At a glance
| Calendar 366 | Calendars by Readdle | |
|---|---|---|
| Pricing | Free plan | Free plan |
| Starts at | $19.99 per year for Pro on the App Store | $19.99 per year, or $3.99 per month (US App Store in-app purchases) |
| Free plan | Free download with basic features. The site does not list which features are premium; all of them can be tried for 7 days before choosing a subscription or a one-time purchase. | a basic calendar with one alert per event. Tasks, multiple accounts, recurring events, natural language input and weather are part of Calendars PRO. |
| Free trial | 7-day trial of all premium features | 7-day free trial of Calendars PRO; the subscription is charged when the trial ends unless canceled |
| macOS | ||
| iOS | ||
| Made by | Vincent Miethe | Readdle Limited |
| Price read from | apps.apple.com | apps.apple.com |
| Checked | Oct 9, 2026 | Oct 5, 2026 |
Who each one suits
Calendar 366
- People who keep everything on Apple devices and want events and tasks in one app
- Mixing iCloud, Google, Microsoft 365, Fastmail and CalDAV accounts
- Buyers who prefer a one-time purchase to a subscription
- Mac users who want to manage their calendar from an AI assistant over MCP
Calendars by Readdle
- People on iPhone, iPad and Mac who want events and tasks in one planner
- Google Workspace users who book rooms and check coworkers' schedules
- Anyone who prefers typing events in plain language
Worth knowing
Calendar 366
- Apple only: iPhone, iPad, Apple Watch and Mac. No Android, Windows or web version is listed.
- After the 7-day trial the free download keeps only basic features, and the vendor does not publish which features are premium.
- Prices appear only as App Store in-app purchases. Several have no billing period, and no monthly price for single-user Pro is shown.
- Siri AI is in beta, English only, and needs iOS, iPadOS or macOS 27. The MCP connection to AI assistants is Mac only.
Calendars by Readdle
- Apple devices only: the App Store listing covers iPhone, iPad, Mac, Apple Watch and Apple Vision. No Windows, Android or web version is listed.
- The free plan is a basic calendar; tasks, multiple accounts, recurring events, natural language input and weather need Calendars PRO.
- Free users get one alert per event, while PRO allows up to five.
- There is no Mac-only purchase: PRO is a single cross-platform subscription, and Readdle says its price varies by region and local taxes.
Key features
Calendar 366
- Natural language entry
- Type what, when and where to create an event or task, with shorthand such as /Work for a calendar, -r1w for a weekly repeat and ! for priority. Apple Intelligence can be picked as the engine on iOS, iPadOS or macOS 27.
- Tasks next to events
- Tasks sit in the calendar with reminders, location-based alerts, priorities and notes, and can be filtered by today, overdue or important. They sync with Apple Reminders, Google Tasks, Microsoft to-dos and Todoist.
- Views and calendar sets
- Year, month, week, day and agenda views, plus month and week views paired with a list, in portrait and landscape. Calendar sets group calendars and lists and sync across devices.
- Meetings and invitations
- Creates Zoom, Google Meet and Microsoft Teams meetings and opens join links for services such as Webex and FaceTime. Invitations arrive in an inbox and can be accepted or declined there.
- Widgets, Apple Watch and menu bar
- 20 home screen and desktop widgets, 6 lock screen widgets and 10 watch complications. The Watch app creates events and completes tasks, and the Mac version adds a full menu bar calendar.
- Shortcuts, URL scheme and MCP
- Supports Apple Shortcuts and a cal366:// URL scheme for automation. On Mac it can connect to Claude Desktop or LM Studio through the Model Context Protocol to show, create and reschedule entries by chat.
Calendars by Readdle
- Several calendar accounts in one view
- Connect Google, iCloud, Outlook and Exchange calendars, color-code them and hide the ones you do not need. Adding more than one account is a PRO feature.
- Tasks next to events
- Tasks sync through Apple Reminders or Google Tasks and appear in the planner with due dates and repeats. Events and tasks can be rescheduled by drag and drop.
- Natural language input
- Type a title such as "Coffee with Alex next Tuesday at 9 am" and the app fills in the date and time. It works in English, German, French, Italian, Spanish and Russian, on PRO.
- Video call links
- Join Zoom, Google Meet or GoToMeeting calls directly from the event, and invite attendees from inside the app.
- Google Workspace rooms and coworkers
- With a Google Workspace account, PRO subscribers can book meeting rooms from an event and view coworkers' schedules next to their own.
- Habit tracker and reflections
- Build routines with a habit tracker, log mood, stress and energy in Personal Reflections, and follow a built-in productivity course.
Plans
Calendar 366
Free$0
Free download with basic features. Neither the site nor the App Store listing says which features stay free after the 7-day trial.
Pro (Yearly)$19.99
per year
Yearly subscription that unlocks the premium features, as labelled in the App Store's in-app purchase list.
Pro (iOS)$19.99
billing basis not shown on the App Store listing
Listed without a period. The vendor's FAQ says a one-time purchase is offered next to the subscriptions.
Pro$49.99
billing basis not shown on the App Store listing
Listed without a period or platform label. The site describes the app as a universal purchase across iPhone, iPad, Apple Watch and Mac.
Pro Family (Monthly)$4.99
per month, or $29.99 per year as Pro Family (Yearly)
Family version of the Pro subscription, with monthly and yearly options in the App Store's in-app purchase list.
Pro Family (iOS)$29.99
billing basis not shown on the App Store listing
Family version listed without a period. A second item named Pro Family, with no platform label, is listed at $69.99.
Calendars by Readdle
Free$0
A basic calendar with one alert per event; the planner features listed under PRO are not included.
Calendars PRO (Monthly)$3.99
per month, US App Store in-app purchase
Tasks, multiple accounts, recurring events, natural language input, up to five alerts, weather and use across Mac, iPhone, iPad and Apple Watch.
Calendars PRO (Yearly)$19.99
per year, US App Store in-app purchase
The same PRO features billed yearly. The US App Store lists one-year items at both $19.99 and $21.99; Readdle's own site cites $19.99.
Ways to pay less
Calendar 366
- Lifetime license
One-time purchase in place of a subscription
The FAQ on Calendar 366's site says that after the 7-day trial you can choose a subscription or a one-time purchase. The App Store lists Pro (iOS) at $19.99 and Pro at $49.99 without a billing period.
Calendars by Readdle
- Annual discount
Yearly PRO costs less than 12 months of monthly
The US App Store lists Calendars PRO at $3.99 for one month and $19.99 for one year, so a year bought monthly would come to $47.88.
- Lifetime license
One-time Lifetime purchase
Readdle announced a Lifetime option in June 2024 at $59.99 in the US, with Family Sharing support. Some major future updates may cost extra.
- Education
Educational discount with a school email
Readdle's Calendars page lets students and educators verify an educational email address to receive a discount link. The size of the discount is not stated.
