Mar 9, 2026

Google Calendar ICS Subscription Refresh Rate: How Often Does It Update?

If you’ve subscribed to a calendar via ICS URL in Google Calendar and new events aren’t showing up right away, you’re not doing anything wrong. Google Calendar just has a slow refresh cycle for external calendar subscriptions.

The Short Answer

Google Calendar refreshes subscribed ICS calendars approximately every 12 to 24 hours.

This is intentional — Google throttles external calendar fetches to reduce server load. The exact timing isn’t published and varies based on how frequently the source calendar is updated, how many subscribers it has, and other factors Google doesn’t disclose.

What This Means in Practice

You subscribe to a calendar at 9am
The calendar owner adds a new event at 10am
You might not see that event until sometime the next day

For calendars that don’t change frequently — sports schedules, holiday calendars, sunrise/sunset times — this is fine. For calendars with rapidly changing events, it can be frustrating.

Can You Force a Refresh?

No. Google Calendar does not provide a button to manually refresh a subscribed calendar. This is a known limitation and one of the most-requested features that Google has not added.

Workarounds people try (and their results):

Remove and re-add the calendar — Some users report this triggers an immediate fetch. Steps: in Google Calendar settings, delete the subscribed calendar, then re-add it from the same URL. Inconsistent results.

Use a different URL format — Switching between https:// and webcal:// URLs sometimes triggers a refresh. Not reliable.

There is no reliable workaround — Google controls the fetch schedule on their end.

Comparison: How Other Apps Handle Refresh

App	Default refresh rate	Can you force a refresh?
Google Calendar	12–24 hours	No
Apple Calendar	Every 15 minutes (configurable)	Yes (pull to refresh)
Outlook	A few hours	No
Fantastical	Follows iOS/macOS calendar sync	Yes
Thunderbird	Configurable (default: 30 min)	Yes

If you need faster updates, Apple Calendar and Thunderbird are significantly better at this.

For Calendar Publishers: How to Speed Up Google’s Fetch

If you’re publishing a calendar (not subscribing to one), a few things help Google fetch it more frequently:

Keep the ICS file small — strip out old events that are no longer relevant
Use standard ICS formatting — non-standard fields can cause parsing delays
Ensure your ICS URL returns proper HTTP headers — include Last-Modified headers so Google knows when the file has changed

These don’t override Google’s throttling but may put your feed in a higher-priority queue.

The Underlying Reason

ICS subscriptions work by having the subscribing app periodically download the entire ICS file from a URL. Google’s servers do this on behalf of all Google Calendar users — potentially billions of fetches across millions of subscribed calendars. Throttling to once per 12–24 hours is a practical necessity at that scale.

Alternatives to ICS Subscriptions

If real-time sync is important, ICS subscriptions aren’t the right tool. Consider:

Google Calendar → Google Calendar: Sharing via Google’s own sharing system updates in real time
Google Calendar → Outlook: Using CalDAV sync or a sync tool like CalendarBridge gives near-real-time updates
Publishing events via API: If you control the calendar, a two-way sync via the Google Calendar API updates in real time