aCalendar vs One Calendar

aCalendar

• Android users who want a full calendar without a subscription
• People who want Google Tasks or Microsoft To Do lists inside their calendar
• Anyone who prefers to buy only the upgrades they need

One Calendar

• People who mix Google, Microsoft, iCloud and CalDAV calendars
• Households or workers split between Android, iPhone and Windows
• Buyers who want a one-time payment and no subscription

aCalendar

• Android only. The vendor states there is no iOS, web or PC version and that none is planned.
• The free version shows ads, and tasks, attendees, profiles, public holidays and the wider color choices all need a paid upgrade.
• In-app upgrades cannot be shared through Google Play Family Library; only the separate aCalendar+ app can.
• Licenses are tied to the store account and cannot be moved between Google Play and Huawei AppGallery.

One Calendar

• A Premium license is needed per platform group: Android, iOS and Windows are each bought separately, because the stores do not allow cross-platform licensing.
• The free version syncs 6 months of past appointments and leaves out search, theming and appointment colors.
• The Microsoft Store page lists the Windows app as free with in-app purchases but does not show the Premium price.
• No web or Linux version is listed. Printing and automatic day rollover are Windows-only Premium features.

aCalendar

Day, week, month, agenda and year views

Swipe vertically to move through time and horizontally to switch views. Day and week views can show a mini month or a graphical week overview alongside.

Eight home screen widgets

Widgets include agenda, date, day and week layouts and a birthday widget added in version 2.9. Accent colors can be set per widget with the Colors upgrade.

Tasks next to events

The Tasks upgrade shows to-dos on their due dates in day, week and month views, with subtasks and a tasks widget. It works with Google Tasks, Microsoft To Do, CalDAV through Tasks.org, and local lists.

Business features

An upgrade adds attendee management, linking contacts to events, free or busy status, private events, and profiles that separate work and personal calendars.

Print and export

Calendar views can be printed or exported as PDF or PNG, and events exported as ICS or CSV files. Multi-select applies an action to several events at once.

Uses Android's calendar sync

The app runs no servers of its own. It reads and writes the calendars Android syncs, including Google Calendar, Microsoft Exchange accounts and CalDAV servers, plus local calendars.

One Calendar

Many calendar services in one app

Connects to Google Calendar, Outlook, Office 365, Exchange, iCloud, Yahoo, GMX, Synology, Nextcloud, ownCloud, Mailbox.org and other CalDAV servers, and shows them together.

Five views with week numbers

Day, week, month, year and list or agenda views, all with week numbers. A quick filter narrows what is shown by calendar color.

Appointments and invitations

Add, change and delete appointments, set up recurrences, invite people to a meeting and accept incoming invitations. Appointments can be shared through apps such as WhatsApp.

Works offline

Appointments can be viewed and managed without an internet connection, according to the vendor's feature list.

Widgets and live tiles

Several widgets are available depending on the operating system, including live tiles on Windows. Choosing which calendars, birthdays and tasks a widget shows is a Premium feature.

Theming and colors

Premium unlocks 170 color options, a background picture, a custom text color and predefined themes, plus a separate color for any single appointment. A dark theme is supported.

aCalendar

• aCalendar$0

  All calendar views, 8 widgets, flexible recurrences, birthdays, moon phases, printing and export. Shows ads, at most one a day according to the vendor.

• In-app upgrades$2.49 - $11.99

  one-time payment per item on Google Play

  Ad-free, Tasks, Business Features, Colors and Holidays bought individually inside the free app. Not shareable through Family Library.

• aCalendar+$11.99

  one-time purchase on Google Play

  A separate paid app with every upgrade included and no ads. It can be shared through Google Play Family Library.

One Calendar

• Free$0

  Day, week, month, year and list views across all connected calendars, with invitations and recurrences and 6 months of past appointments.

• Premium$5.99

  one-time payment per platform group (App Store or Google Play)

  Appointment colors, theming, search, 3 years of history, widget configuration, immediate sync and navigation. Windows needs its own license.

aCalendar

• Other savings

  Family Library sharing for aCalendar+

  Bought as a paid app after July 2, 2016, aCalendar+ can be shared with up to 5 family members through Google Play Family Library. In-app upgrades are not eligible.

One Calendar

No public discounts listed.