_v1•ResyncGuide
Short answer: pick the direction you actually need. To see an Outlook.com or Microsoft 365 calendar in Google Calendar, publish the Outlook calendar as an ICS URL, then add it in Google Calendar under Other calendars From URL. That is one-way and read-only. Google refreshes subscribed calendars on its own schedule, which can be hours. Microsoft Power Automate can copy Outlook events into Google Calendar, usually with titles, and a create-only flow will not keep later edits or deletions in sync. Work or school tenants can block publishing and third-party connectors. Resync works only with Google Calendar accounts. It does not sync Outlook, Microsoft 365, or Outlook.com.
Anyone with a published ICS link can view that calendar at the detail level you chose. A one-time .ics import is a snapshot, not ongoing sync. True two-way Outlook-to-Google sync needs a third-party tool. If meetings already live on another Google calendar and you want busy/free there without sharing titles, Resync can write private Busy holds on the Google side.
Google Calendar cannot sign in to Outlook. The official path is to publish the Outlook calendar, then subscribe Google to that URL. Microsoft documents Publish a calendar in Outlook on the web, and the same publish steps on Outlook.com. HTML and ICS calendars are read-only. Anyone with the link can view the calendar at the detail level you published, from busy time to full event details.
Work and school accounts are different from personal Outlook.com. Microsoft Support notes that calendar sharing may not be available, or may be limited to people in your organization, depending on organization settings. Microsoft Learn says calendar publishing needs a sharing policy with an Anonymous entry that permits calendar sharing. If Publish a calendar is missing, that is usually an admin block, not a Google problem.
Microsoft Support, Microsoft Learn, and Google Calendar Help steps checked Nov 6, 2026. Cited from Share your calendar in Outlook on the web, Share your calendar in Outlook.com, Publish and subscribe to calendars in Exchange Online, and Subscribe to someone else's calendar.
The other direction is also an ICS subscription, just reversed. Copy Google Calendar's secret address in iCal format, then in Outlook choose Add calendar → Subscribe from web. That Google copy in Outlook is read-only. Outlook on the web can take more than 24 hours to refresh a subscribed calendar. The full Google-into-Outlook steps are in the Outlook guide.
If you are moving off Outlook rather than keeping both calendars in sync, download an .ics file and import it into Google. That is a snapshot. Later Outlook changes do not follow.
Google Calendar Help says imported events do not stay in sync. A later export and import can leave a second copy. Do not import the same file on top of a live From URL subscription. The import ICS guide covers upload errors, and the duplicate-events guide covers cleanup.
Google Calendar Help steps checked Nov 6, 2026. Cited from Import events to Google Calendar.
Power Automate is Microsoft's flow tool. It has an Office 365 Outlook connector and a Google Calendar connector. A common template creates a Google event when an Outlook event is created. That writes a real event onto Google, so booking tools that check that Google calendar can see the time as busy.
Microsoft Learn connector docs checked Nov 6, 2026. Cited from Office 365 Outlook connector and Google Calendar connector.
Microsoft's publish path is one-way into Google. Google's iCal path is one-way into Outlook. Power Automate copies are one-way unless you build both directions yourself. None of those official options is live two-way sync between an Outlook calendar and a Google calendar.
If you need live two-way sync between Outlook calendars and Google Calendar, that takes a third-party calendar sync tool that connects both accounts. Those tools vary in what they copy, how fast they refresh, and whether they write busy holds or full events. This page does not name, rank, or price them.
Showing Google calendars in Apple Calendar or Samsung Calendar is a different official path: add the Google account in that app. Resync does not connect Outlook on those devices either.
| Method | Direction | Live or delayed | Best for |
|---|---|---|---|
| Publish Outlook ICS into Google | One-way, Outlook to Google. The Google copy is read-only. | Delayed. Google refreshes From URL feeds on its own schedule, often hours later. | A read-only view of Outlook.com or Microsoft 365 inside Google Calendar. Choose busy-only if you do not want titles in the feed. |
| Export .ics and import | One-time copy. No ongoing direction after import. | Not live. Imported events do not stay in sync. | Switching to Google once, or moving a snapshot of Outlook events. |
| Power Automate copy flow | One-way copies from Outlook into Google unless you build a second flow the other way. | Depends on the trigger. Create-only flows miss later edits and deletions. | Writing real Google events from new Outlook bookings, if your tenant allows the connectors. |
| Third-party two-way tool | Two-way Outlook and Google, if the tool supports both. | Depends on the tool. This page does not name or price them. | When you need live two-way sync between Outlook calendars and Google Calendar, including busy-only copies. |
| Resync Busy holds | Two-way blocking between Google calendars only. Not Outlook or Microsoft 365. | Google push notifications, plus a polling fallback about every 5 minutes. 90-day window. | Several Google accounts that should treat each other's busy time as busy, without sharing titles. |
Start with where the events are missing. If they never appear in Google Calendar on a computer, the ICS URL or the publish setting is the problem. If they look right on calendar.google.com and only gone from a phone, that is mobile delay after a computer From URL add. If they appear twice, you probably stacked two methods.
| Symptom | Likely cause | Fix |
|---|---|---|
| Thought it was two-way | An ICS subscription is one-way. Edits in Google Calendar do not write back to Outlook. A create-only Power Automate flow is also one-way. | Keep Outlook as the source of truth for those events, or use a third-party two-way tool. Do not edit the Google overlay and expect Outlook to change. |
| Duplicate events | The same Outlook busy time reached Google twice: a From URL overlay plus a Power Automate or import copy, or two imports of the same file. | Hide the extra calendar first. Delete true copies only after you know which copy should keep updating. See the duplicate-events guide. |
| Cannot publish the calendar | Work or school sharing policy can disable anonymous publishing. Microsoft Learn says the sharing policy must include an Anonymous entry that permits calendar sharing. Microsoft Support also notes sharing may be limited to people in your organization. | Ask your admin whether calendar publishing is allowed. Sharing the calendar with a person is not the same as publishing an ICS URL. Personal Outlook.com accounts can usually publish. |
| Outlook events stale in Google Calendar | A From URL subscription is a polled copy. Google fetches it later. There is no refresh button. The Google Calendar app on a phone only shows it after you add the URL on a computer, and the app can lag further. | Confirm the Outlook calendar is still published and the URL still works. Wait for Google's next fetch, or remove and re-add the URL. See the subscribed calendar guide. |
| Booking tools still see you as free | A From URL calendar is an overlay under Other calendars. It does not write events onto your primary Google calendar, so tools that only check that calendar still see you as free. | Use a copy that writes events onto the Google calendar people book, or keep the meetings on a Google calendar and use Resync Busy holds between Google calendars. |
Seeing several Google accounts together, without Outlook, is in the multiple-accounts guide. Keeping two Google calendars from double-booking is in the two-calendars guide. Showing busy time from one Google calendar on another without titles is in the busy-time guide.
Microsoft Support and Google Calendar Help steps checked Nov 6, 2026.
Resync works only with Google Calendar accounts. It does not sync Outlook, Microsoft 365, Outlook.com, Apple Calendar, or iCloud. Use the official steps above to see Outlook in Google Calendar or Google in Outlook. Use Resync only if the real goal is keeping several Google calendars or Google accounts in sync.
If meetings already live on another Google calendar and you want busy/free on Google without sharing titles, Resync can do that on the Google side. It reads when you are busy on Google calendars you mark as sources and writes hold events onto Google calendars you mark as mirrors. $1.50/month or $9/year after a 30-day free trial, no credit card required.
Not with the built-in ICS path. Publishing an Outlook calendar and adding that ICS URL in Google Calendar is one-way and read-only. Edits in Google Calendar do not write back to Outlook. Microsoft Power Automate can copy new Outlook events into Google Calendar, but a create-only flow is still one-way and does not keep later edits or deletions in sync. True two-way Outlook-to-Google sync needs a third-party tool that connects both accounts.
In Outlook on the web or Outlook.com, open Calendar settings → Shared calendars, publish the calendar, choose how much detail the link should include, and copy the ICS URL. In Google Calendar on a computer, add it under Other calendars → From URL. Google Calendar Help says you add a calendar from URL on a computer, not in the Calendar app. Anyone with the published link can view that calendar at the detail level you chose.
No. A calendar added From URL is a read-only ICS copy. Google Calendar Help does not publish a refresh interval you can set and does not document a refresh button. Changes can take hours to appear. Microsoft documents that how often an ICS calendar syncs depends on the recipient's email provider. The subscribed calendar guide covers stale From URL feeds. Phones only show that overlay after you add it on a computer, and the app can lag further behind.
It can copy events, not replace a live two-way sync. Power Automate has Office 365 Outlook and Google Calendar connectors, so a flow can create a Google event when an Outlook event is created. Typical create-only templates copy titles and details unless you change the action. They often skip later updates and deletions, can duplicate events if you also subscribed to the ICS feed, and may expand recurring Outlook events into separate Google events. Work tenants can block the Google connector.
Duplicates usually mean the same busy time reached Google twice: a From URL overlay plus a Power Automate or import copy, a one-time import on top of a live subscription, or two tools writing the same Outlook event. Hide the extra calendar first. Delete true copies only after you know which copy is the live one. The duplicate-events guide covers that cleanup.
No. Resync works only with Google Calendar accounts. It does not sync Outlook, Microsoft 365, Outlook.com, Apple Calendar, or iCloud. Publish an Outlook ICS URL into Google if you need that overlay. If meetings already live on another Google calendar and you want busy/free there without sharing titles, Resync can write private Busy holds on the Google side. $1.50/month or $9/year after a 30-day free trial, no credit card required.
Connect the Google calendars you want to keep aligned, then mark sources and mirrors on the dashboard.
Resync will ask Google for permission to:see your list of calendars; see events on the calendars you choose as Sources, to know when you're busy; and create, update and delete events titled "Busy" on calendars you choose as Mirrors. We never store event titles, attendees or locations. Privacy policy
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