Original reference guides · Reviewed 8 October 2026
Import or subscribe? Choose before troubleshooting
Start here when: events arrived once, but later changes never appeared.
An imported file is a snapshot. A subscription lets a calendar application retrieve a published feed again. Renaming a downloaded file or importing a newer copy does not turn the first import into a subscription. For a one-time migration, a snapshot may be exactly what you need; for a changing timetable, first look for the publisher's subscription option. Microsoft explains the distinction.
Pick the right route
- Google Calendar on a computer: Settings → Import & Export accepts an ICS file and lets you select a destination calendar. Extract individual ICS files from a ZIP first. Google warns that imports omit guests and conferencing data, and imported events do not keep two accounts synchronized. Google import instructions.
- Apple Calendar on Mac: File → Import accepts an ICS file, then asks which calendar should receive it. An ICBU archive is different: Apple warns that importing an archive replaces current calendar information. Check the extension before proceeding. Apple import instructions.
- Outlook.com / Outlook on the web: Add calendar offers Upload from file and Subscribe from web. The latter needs a feed address. Microsoft says subscription changes can take more than 24 hours to appear; repeated imports are not a reliable refresh button. Microsoft instructions.
A useful diagnostic record
Write down the source address or filename, download time, destination calendar, and one event's expected date. Check that the destination is visible before concluding that nothing imported. For a subscription, compare one changed event at its source with the copy in your calendar. Record when you checked rather than repeatedly adding the same feed.
On Apple devices, the account chosen for a subscription matters. Apple's current guidance uses iCloud to make a subscription available across devices signed into the same Apple Account. A calendar appearing on one device is not, by itself, evidence that its ICS content is broken. Apple subscription guide.