Outlook calendar not updating in Google Calendar
You add a meeting in Outlook. Hours later it still is not in Google Calendar. Nothing is broken — you are looking at two separate caches stacked on top of each other, and neither one has a refresh button.
The short version: an ICS subscription is a poll, not a sync. Google Calendar
decides when to fetch your feed, and Google does not document that interval anywhere in its
Calendar help, nor expose any way to change it — reported waits run from a few hours to about a
day. Microsoft adds a second delay by serving its published .ics from a cache of its own.
You cannot force a refresh of an existing subscription. What you can do is
re-add the feed under a new URL, which Google treats as a new calendar and
fetches immediately, or stop using ICS and
switch to a real sync mechanism.
Why there is no refresh button
"Add by URL" in Google Calendar creates a subscription. Google's servers fetch that URL on a schedule of their own choosing and cache the result; your browser is never involved. Two consequences follow that surprise most people:
- Reloading Google Calendar does nothing. You are re-rendering Google's cached copy, not re-fetching the feed.
- The feed being correct right now does not mean Google has seen it. Open the ICS URL in a browser and you will often see an event that Google is still missing. That is expected, and it is a useful diagnostic: if the event is not in the raw feed either, your problem is on the Microsoft side, not the Google side.
Microsoft contributes the other half. A published Outlook calendar is not generated per request —
it is produced periodically and served from cache, so a change in Outlook is not necessarily in the
.ics the moment you make it. Stacked, the worst case is Microsoft's cache interval plus
Google's polling interval.
Do not confuse this with an import. If you used Import and selected a
downloaded .ics file, you copied events once. They will never update, because there is
nothing left pointing at Outlook. Delete them and subscribe by URL instead.
What actually works: change the URL
Google keys its cache to the subscription URL. Give it a URL it has not seen and it fetches immediately, because there is nothing cached to serve. So:
- Remove the existing subscription (hover the calendar in the left sidebar → ⋮ → Unsubscribe).
- Add the feed again with a harmless extra query parameter, for example
…/reachcalendar.ics?v=2. Any parameter the server ignores will do.
This is a way to force one fetch, not a way to speed up future ones. Once subscribed, the new URL goes back to the same undocumented polling schedule. It is genuinely useful in two situations: you just fixed something and want to confirm the fix, or the subscription has gone stale and stopped updating entirely.
If you are already routing the feed through the time zone fix proxy, you get this for free — change any parameter in the generated URL and Google sees a new calendar.
Check where the delay actually is
Before assuming it is Google, find out whether the event has even reached the feed. Open your
published .ics URL directly in a browser, or run it through the
diagnostic mode of the proxy, and search for the event.
| Event is… | Where the delay is | What to do |
|---|---|---|
Not in the raw .ics |
Microsoft's publish cache | Wait. Re-publishing the calendar in Outlook settings regenerates the link and forces fresh output, but it invalidates the old URL and every subscription to it. |
In the .ics, not in Google |
Google's polling interval | Re-subscribe under a modified URL. |
| In Google, at the wrong time | Not a sync problem at all | See the time zone fix. |
| In Google, then disappears again | Usually a revoked publish link | See feed won't load. |
If hours of lag is not acceptable
Then ICS is the wrong tool and no amount of tuning will fix it. A subscription is read-only and poll-based by design. The realistic options:
| Option | Lag | Two-way? | Trade-off |
|---|---|---|---|
| ICS subscription (what you have) | Hours | No | Free, no permissions, works with any calendar. Slow and read-only. |
| Microsoft 365 ↔ Google via a paid sync service | Minutes | Yes, usually | Costs money and gets full mailbox access to both accounts. Check what your employer allows before connecting a work calendar. |
| Your own script against the Microsoft Graph and Google Calendar APIs | Whatever you schedule | Yes, if you build it | Full control, no third party. Needs app registration on both sides and ongoing maintenance. |
| Add the Outlook account directly to your phone's calendar app | Push, near instant | Yes | Sidesteps Google Calendar entirely. Both calendars show side by side on the device instead of one containing the other. |
Questions
How often does Google Calendar refresh a subscribed ICS feed?
Google does not publish a figure, and its Calendar help pages on adding a calendar by URL say nothing about refresh frequency or how to change it. Users commonly report anywhere from a few hours to around 24 hours. Treat any specific number you read as an observation, not a specification — it is not a documented guarantee and Google is free to change it.
Can I force Google Calendar to refresh a subscription now?
Not for an existing subscription — there is no manual refresh and reloading the page only re-renders Google's cached copy. The working alternative is to unsubscribe and re-add the feed with a modified URL, such as an extra ignored query parameter. Google has no cache for that URL, so it fetches immediately.
Why does the ICS file show my new event but Google does not?
Because Google has not polled the feed since you added it. This is the normal case and it confirms the Microsoft side is working — the delay is entirely Google's polling interval.
Does using a proxy make the feed refresh faster?
No, and any tool claiming otherwise is misleading you. Google's polling interval is Google's decision and nothing in the path can change it. A proxy only controls what Google receives when it does poll — which matters for correctness, not for speed.
My subscription updated for a while and then stopped completely.
That usually means the feed is now failing rather than being slow — most often a publish link that
was regenerated or revoked in Outlook. Open the URL in a private browser window: if you get an error
page or a sign-in prompt instead of a wall of text starting with BEGIN:VCALENDAR, see
feed won't load.