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Import an ICS file into Proton Calendar Free

Import a small calendar file into Proton Calendar Free and check the date, time zone and details before moving a whole calendar.

HoldMyTwist · 2 min read

Calendar cards moving from a navy folder into an open planner

An ICS file can carry calendar events between services. Import a small file first and check the result before moving an entire calendar.

This example imports one fictional all-day event on Free. It does not connect another provider or send invitations.

Before you start

You need a Proton account for the Calendar web app. Create a Proton Mail Free account (opens in a new tab), which includes Calendar, or sign in with your existing account. Have a small, harmless .ics file ready and keep the original.

If the ICS arrived in Proton Mail, check the email's event controls first. Proton's inbox guide (opens in a new tab) explains both options: Add to Proton Calendar adds an event without notifying the sender, while invitation responses such as Yes, Maybe or No send your response to the organizer.

1. Prepare the calendar file

  1. Export an .ics file from your current calendar using that service's export controls. Keep the original.
  2. Start with a small test calendar or one harmless event.
  3. Check Proton's limits (opens in a new tab): at most 10 MB and 15,000 events per import. Other formats are not accepted.

2. Import through settings

  1. Open Proton Calendar (opens in a new tab).
  2. Open Settings, then All settings. Select Import/export.
  3. Click Import from ICS and choose your file.
  4. Check the destination calendar if the form asks you to choose one. The example account has one calendar.
  5. Click Import. Keep the tab open until completion.

Watch out

A completed import can still omit unsupported details. Proton says event participants are not imported, and some recurrence rules are unsupported. Read any warning, then check representative events yourself. Keep the old calendar until dates, times and repeats match what you need.

3. Verify an imported event

  1. Close the completion message and return to Calendar.
  2. Navigate to a date from the file.
  3. Open the event. Check its title, date and description. For timed events, check the time zone too.
  4. For repeating events, check several occurrences.

Imported fictional all-day event in Proton Calendar

Imported fictional all-day event in Proton Calendar
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If the import fails or looks incomplete

Check the .ics extension and size. Proton supports dates from 1970 through 2037 and does not import tasks or journals. Read its unsupported-data list before retrying. Importing the same events again can overwrite existing events, so check before repeating an import.

Want to try a small calendar import first? Create a Proton Free account with Calendar (opens in a new tab) and import a harmless test event. Keep your original calendar until the dates, times and repeats you need match.

Source: ICS requirements and unsupported data (opens in a new tab).

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