How Often Does Google Calendar Refresh ICS Subscriptions?
The numbers on this page are the reference facts for how often Google Calendar actually re-fetches a subscribed ICS calendar — measured, sourced, and last reviewed in July 2026.
Short answer
Google Calendar refreshes calendars subscribed via URL (ICS) roughly every 12–24 hours. Google publishes no official interval, provides no manual refresh button, and offers no setting to speed it up. If you need Outlook changes in Google Calendar faster than that, you need push-based sync instead of an ICS subscription.
What is the actual refresh interval?
Independent measurements over the years consistently land in the same band: a subscribed ICS feed is fetched about once every 12 to 24 hours, with occasional stretches beyond 24 hours. Google’s own help page for adding calendars from a URL currently states no number — so any site quoting “Google says 12 hours” is citing text that no longer exists. Treat the interval as undocumented, uncontrollable, and slow.
How do the major calendar apps compare?
| Platform | Typical refresh | User-configurable? | Manual refresh? |
|---|---|---|---|
| Google Calendar | ~12–24 hours | No | No |
| Apple Calendar (macOS/iOS) | Weekly by default | Yes — 5 min to weekly | Yes |
| Outlook (subscribing to external ICS) | A few hours in practice; Microsoft warns it can exceed 24h | No | No |
Why does this matter for Outlook-to-Google sync?
The standard free advice — publish your Outlook calendar, subscribe in Google via From URL — inherits this delay twice. Microsoft warns that subscription updates can sometimes take more than 24 hours on its side, and Google then waits up to another day to fetch the feed. For a calendar you plan your day around, that means this morning’s reschedules routinely miss today entirely. The delay is also the root cause behind most “Outlook calendar not syncing” complaints — the sync isn’t broken, it’s just a day behind by design.
What are the faster alternatives?
- Push-based cloud sync— reads changes from Microsoft’s change notifications and writes them to Google within about a minute. This is how Calendar Syncer works.
- A desktop tool on an always-on Windows PC — OGCS syncs every few minutes while the machine is awake.
- Living inside Outlook instead — subscribing to your Google calendar from Outlook refreshes faster than the reverse direction, if working from Outlook is an option for you.
For the full decision, see every Outlook-to-Google sync method compared.
Frequently asked questions
Can I force Google Calendar to refresh a subscribed calendar?
No. Google Calendar offers no manual refresh for URL-subscribed calendars, on web or mobile. Removing and re-adding the subscription triggers one immediate fetch, but the schedule afterwards returns to roughly every 12–24 hours.
Does Google publish an official ICS refresh interval?
No. Google's current help page for adding calendars from a URL states no interval at all. The 12–24 hour figure comes from consistent real-world measurements by multiple independent sites and years of user reports in Google's own community forums.
Why does my subscribed Outlook calendar sometimes lag more than 24 hours?
Two delays stack: Microsoft warns that calendar subscription updates can sometimes take more than 24 hours on its side, and Google adds its own 12–24 hour fetch cycle on top. In the worst case an Outlook change waits a full publishing cycle plus a full fetch cycle before Google shows it.
Is Apple Calendar faster than Google Calendar at refreshing subscriptions?
Yes. Apple Calendar lets you choose the refresh frequency per subscription — as often as every 5 minutes on macOS. Google Calendar has no equivalent setting anywhere.