How often does Google Calendar refresh ICS subscriptions?

Short answer: Google Calendar refreshes an ICS subscription roughly every 8–24 hours, and there is no button to force it. There's no documented SLA — in practice we've seen Google take anywhere from a few hours to a couple of days to pick up a change. If you just added a feed and it looks empty, the events are usually there — Google hasn't fetched them yet.

The good news: most lunar calendar feeds (including MoonCal) include 20 years of pre-computed events in every fetch, so Google's slow refresh almost never affects the dates you actually care about. The bad news: if you edit an event today, Google may not show that edit for a day or more.

Refresh intervals by calendar app

These are the typical refresh frequencies for ICS subscriptions. The actual numbers are not advertised by any of these vendors — they come from community reports and our own testing.

Why is my subscription showing the wrong events (or nothing at all)?

Most subscription problems fall into one of four buckets. Try them in order:

1. The feed is correct, the app just hasn't fetched it yet. Wait 24 hours, then check again. In Apple Calendar you can right-click the calendar in the sidebar and choose "Refresh".
2. You subscribed to the wrong URL. Open the URL in a browser — it should download a .ics file starting with "BEGIN:VCALENDAR". If you see HTML, an error page, or a login screen, the URL is wrong.
3. The feed was regenerated. In MoonCal, clicking "Regenerate URL" invalidates the old link immediately. Subscriptions added under the old URL will keep returning empty until you remove and re-add them.
4. The calendar was deleted. MoonCal soft-deletes calendars for 90 days before purging. During this window the URL returns an empty VCALENDAR, so your calendar app shows the subscription but with no events. Either restore the calendar or remove the subscription.

How MoonCal handles the slow-refresh problem

MoonCal can't force Google to refresh faster — nobody can. What we do instead is bake the future into the feed.

• Every fetch of your subscription returns 20 years of pre-computed lunar-to-Gregorian conversions. Your 2027 birthday is already in the feed Google grabbed last month.
• Each event includes both a 1-day and 3-day VALARM, so birthday reminders fire even when the feed hasn't refreshed in a while.
• For new or edited events to appear, your calendar app needs to fetch the feed at least once. Apple Calendar at "Every hour" is reliable; Google Calendar requires patience.
• If you can't wait, the simplest workaround is to remove and re-add the subscription. The app will fetch fresh data immediately.

When to give up on Google Calendar refresh

If you need near-real-time updates to lunar events on Android or iOS, the cleanest path is to use Apple Calendar (if you're on iOS) or a third-party app that supports CalDAV with a short refresh interval. ICS subscriptions are designed for low-frequency, append-only data — exactly the kind of data lunar festivals and birthdays produce, so the model usually works fine.