Subscribe to an external calendar

8 mins
Calendar sharing and subscription

Proton Calendar(new window) allows you to add the calendars of friends, family, colleagues, and organizations that do not use Proton Calendar so you can keep track of all their upcoming events in one convenient and secure app. To add an external calendar, simply subscribe to its public address link.

Regardless of your Proton subscription plan, you can subscribe to up to five external calendars and read their events. However, you will not be able to edit or delete the events on any external calendar you are subscribed to.

This feature is currently available to Proton Calendar beta testers. If you would like to help improve our products and gain early access to features such as subscribing to an external calendar, you can enable beta access in our web app:

1. Log in to the Proton Calendar(new window) web app.

2. Go to SettingsBeta access.

Beta Access option
(new window)

3. Check the box to Enable Beta Access and click Apply.

Enable Beta Access checkbox

Most popular calendar apps allow you generate a shareable link similar to how Proton Calendar does. To subscribe to an external calendar, the owner of the calendar must share this link with you or make it public.

The owner of the calendar might also be able to set different access and permission levels (i.e., they might decide that you will only be able to see the times when an event is taking place, not the event details themselves). 

To change your permission level for a calendar, you must speak to the calendar owner and request a new link. 

Google Calendar

To request a link from someone who uses Google Calendar:

  1. On a computer, open Google Calendar(new window). (You can only get the link you need from the Google Calendar for web, not the mobile Google Calendar apps.)
  2. In the top right, click the settings gear wheel icon → Settings(new window).
  3. On the left side of the screen, click the name of the calendar you want to share.
  4. Scroll down to Integrate calendar and copy the link in the Secret address in iCal format field. This link can be added to Proton Calendar using the instructions below. 

(new window)

Please note that you can’t share a Google Family calendar using this method. Google does not allow you to share Google Family calendars with people that are not members of your family group.

Outlook Calendar on the Web

To request a link from someone who uses Outlook Calendar Web (or

  1. Open Outlook, go to Calendar view, click the settings gear wheel icon → View all Outlook settings.
  2. Select Calendar → Shared calendars.
  3. Under Publish a calendar, select the calendar you want to publish and how much detail you want to share.
  4. Click Publish.
  5. Copy the link in the ICS field. This link can be added to Proton Calendar using the instructions below. 

(new window)

If these instructions are not right, they might be using classic Outlook on the web. You can find those instructions here(new window). Be sure they follow the instructions under Publish and share the ICS link.


1. Open Nextcloud and go to your Calendar tab.

2 a. If the calendar you wish to share has not been shared before, it will show a Share icon. Click on it.

If the calendar has not been shared

Go to Share link+ to publish the calendar.

Publish calendar

2b. If the calendar you wish to share to has been shared before, it will show a Link icon. Click on it.

If the calendar has been shared before

3. Go to Share linkCopy subscription link.

Copy subscription link

Proton Calendar

To request a link from someone who uses Proton Calendar, send them the link to this Support article: How to share a Proton Calendar with a link(new window).

Public calendars

Country and city public websites usually provide a calendar of holidays and other public events via a URL you can subscribe to or an ICS file you can import. Here is one example of a website that provides calendars that track each country’s official holidays: window)

How to subscribe to an external calendar

  1. Once you have a calendar link, log in to the Proton Calendar(new window) web app and click Settings → Go to Settings → Calendars → Subscribed calendars.
  2. Click on the Add calendar button. This will open a new window where you will need to paste the calendar URL and click Add calendar.

Proton Calendar will immediately create a new calendar, but it may take several minutes for all its events to show up.

You can change the name and description of an external calendar by clicking the Edit action button next to it in the Subscribed calendars section. (Note: You cannot edit a calendar until it is fully  synchronized.)

External calendars that you subscribe to allow you to view calendar events (depending on the permission level of the link), but you cannot edit or delete these events. You also cannot set an external calendar as your default calendar, cannot share or export it, and cannot import events to it. 

External calendars don’t count toward your limit of personal calendars and are listed under Subscribed calendars

List of subscribed calendars
(new window)

Unsubscribe from a calendar

  1. Log in to Proton Calendar(new window) and click Settings → Go to Settings → Calendars → Subscribed calendars.
  2. Click the action button next to the corresponding calendar and select Remove from the dropdown menu. 

This will remove the calendar along with all its events.


Calendar not synced

If you see a not synced warning next to an external calendar that you have subscribed to, hover your mouse over the not synced alert for more information on the problem.

Calendar not synced warning

You will see one of the following messages:

  • More than 12 hours passed since last update — We haven’t been able to update the calendar or fetch the event in the last 12 hours. Proton Calendar will try again, so please wait to see if the problem resolves itself before contacting support(new window).
  • Unsupported calendar format — The calendar cannot be synced because it uses a different format from the iCalendar(new window) standard that we follow. Please verify that you are exporting the correct link before contacting support(new window) for further assistance.
  • Calendar is too big — The calendar is too large to be imported. Please see the section below for how this can be fixed if you are exporting from Google Calendar.
  • Calendar link is not accessible — The link cannot be accessed from outside the calendar provider’s ecosystem. A good example of this is a corporate calendar that cannot be shared outside the company. It is not possible to subscribe to such calendars.
  • Calendar link is temporarily inaccessible — The link did work, but may have been deleted or edited by the external provider. Please verify that the link is still valid.

Calendar is too big (Google Calendar)

If you are exporting from Google Calendar and the not synced warning says Calendar is too big, you can reduce its size by only importing events after a specified date and time. Any events older than the specified date will not be imported to Proton Calendar.

To do this, you need to edit the calendar link by adding the following to the end of the URL:


For example:

In the above example, all events in the calendar that occur before 01 January 2022 will not be imported to Proton Calendar, thus reducing the size of the calendar. 

Unfortunately, this trick only works with calendars exported from Google Calendar. 

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