Two-Way Sync Between Google Calendar and Outlook (2026 Guide)
“Two-way sync between Google Calendar and Outlook” sounds like a feature either Google or Microsoft would have built into their products by now. They haven’t. Native subscriptions in either direction are read-only — useful for visibility, useless for editing. This guide covers why that’s the case, what the manual options actually deliver, and how to get true bidirectional sync.
Quick answer
- Native two-way sync between Google Calendar and Outlook does not exist. Both apps can subscribe to the other’s ICS URL for read-only updates only.
- One-way snapshot import (export from one, import to the other) is fine for migration but doesn’t keep them in step.
- For true two-way sync — edit in either calendar, change replicates within minutes — you need a third-party tool. XCalSync does this.
The rest of this guide unpacks why the native options fall short and what XCalSync gives you instead.
Going one direction only? See How to sync your Outlook Calendar with Google or How to sync Google Calendar to Outlook.
Why Google and Outlook don’t do native two-way sync
Both support ICS subscription URLs, which are HTTP fetches of an iCalendar file at a published URL. Outlook can subscribe to a Google Calendar’s secret iCal URL; Google can subscribe to an Outlook calendar’s published ICS URL. In both cases:
- The subscription is read-only. The destination has no authenticated channel back to the source’s authoritative store. It can read; it cannot write.
- The refresh is slow. Google fetches subscribed calendars every 8–24 hours. Outlook fetches roughly every 3 hours. Neither has a manual refresh.
- There’s no conflict resolution. If you could write back, neither protocol defines what happens when the source event was edited between fetches.
This is why every “make Google Calendar sync with Outlook” article you’ve read so far gives you import or subscribe — not real bidirectional sync. The protocol the apps speak natively (HTTP + ICS) only goes one direction.
The fix has to come from a system that authenticates to both sides separately and reconciles changes. That’s what XCalSync does using the official Google Calendar API and Microsoft Graph.
What “two-way sync” actually means
Three things people often conflate when searching for “two-way sync”:
- Visibility both ways. I see Google events in Outlook and Outlook events in Google. Solvable with two read-only subscriptions, one in each direction. Available natively, but slow.
- Editing in either direction. Edit a Google event from Outlook (or vice versa), and the source updates. Not available natively.
- Mirrored full state. Anything in calendar A also exists in calendar B as native, editable events; deletes in either also propagate. Not available natively.
If you only want visibility, the native subscription approach works — it just refreshes slowly and is read-only. If you want #2 or #3, you need a third-party sync layer.
Native subscription: the read-only fallback
If you only need to see the other calendar in your primary view (no editing), the native subscriptions cover both directions:
Subscribing Outlook to a Google Calendar
- In Google Calendar, hover over the source calendar → three-dot menu → Settings and sharing.
- Scroll to Integrate calendar and copy the Secret address in iCal format.
- In Outlook on the web, open Calendar → Add calendar → Subscribe from web.
- Paste the URL, name it, click Import.
Subscribing Google to an Outlook Calendar
- In Outlook, open Calendar settings → Shared calendars → Publish a calendar, pick the source, set permissions to Can view all details, click Publish, copy the ICS URL.
- In Google Calendar, click + next to Other calendars → From URL, paste the URL, click Add calendar.
Doing both directions gives you visibility on each side. The two big caveats:
- Both calendars are read-only. You can’t edit from the destination.
- Refresh is slow. Up to 24 hours on the Google side, ~3 hours on Outlook’s. New events created in the source might not appear in the destination until the next day.
For “I want to glance at my work calendar from my personal Google” use cases, this is fine. For active scheduling, it isn’t.
True two-way sync with XCalSync
XCalSync connects to both Google Calendar and Outlook through their official APIs, mirroring events as native, editable items in the destination. Edits in either calendar propagate to the other on the next sync cycle.
What it does
- Two-way mirror. Create, edit, or delete an event in either calendar — the change replicates to the other within minutes.
- Native events on both sides. No read-only overlay. The destination has full edit access because it’s a native event, not a subscription preview.
- Selective filters. Only sync weekdays, only events matching a title, only events with certain attendees, skip “tentative” or “free” status events.
- Title rewriting. Replace “Coffee with Sara at Maru” in your personal calendar with “Busy” in the work calendar so colleagues see availability without reading personal details.
- Buffer time. Add a 15-minute pre/post buffer to copied events.
- Authenticated, not URL-based. Uses OAuth via Google Calendar API and Microsoft Graph. No public ICS URLs to leak or rotate.
What it doesn’t do
- It’s not literally real-time. Sync runs every few minutes, not instantly. For most scheduling use cases, “within five minutes” is indistinguishable from instant.
- Attendee invitations don’t fork. A meeting created in Google with three invitees stays a Google meeting from the attendees’ perspective. The mirrored Outlook event shows the attendees as text but doesn’t trigger a separate Outlook invite.
- Some Microsoft-only fields don’t survive. Teams meeting links, Outlook-specific properties like “follow up flag”, and similar don’t have Google equivalents.
Setup
- Sign up at app.xcalsync.com.
- Click Add account → Google, sign in to your Google account, grant calendar access via OAuth.
- Click Add account → Outlook, sign in via Microsoft, authorize.
- Create a SyncPair: Google calendar → Outlook calendar, direction: two-way, optional filters.
- Save. The first sync runs immediately; subsequent syncs run on a schedule of minutes.
Free tier
The free tier covers a single SyncPair, configurable as two-way. Paid plans start at $4/month for up to two calendars, or $8/month for up to ten.
Common “two-way sync” gotchas
Setting up two one-way SyncPairs in opposite directions
This creates duplicates because each direction sees the events the other just created and copies them back. Always use a single two-way SyncPair, never two one-way pairs in mirror.
Time zones
Sync respects the source event’s time zone. If your two accounts are configured with different time zones, events appear at “the same time” semantically but display at different clock times in each. Set both calendars to the same time zone if that’s confusing.
Recurring events with custom exceptions
Edge cases — “every Monday except the second one in November” — sometimes don’t survive the round trip. Spot-check recurring meetings after the first sync. If a series imports as a single occurrence, simplify the recurrence rule on the source.
Workspace admin restrictions
Some Microsoft 365 and Google Workspace admins restrict third-party OAuth apps. If XCalSync’s connection request is blocked, you’ll see an admin-approval message during sign-in. Ask your admin to approve XCalSync’s calendar scopes — most do, since it’s narrower than full mailbox access.
Deletes propagating both ways
By default, a two-way SyncPair propagates deletes in both directions. If you want to mirror creations and edits but not deletions (e.g., to keep a backup of personal events in your work calendar), configure the SyncPair to skip delete events.
Picking the right approach
| What you want | What works |
|---|---|
| See Outlook events in Google or vice versa | Native subscription, refresh delay 8–24h |
| One-time copy from Outlook to Google or reverse | Native export and import |
| Edit events from either calendar, with live updates | XCalSync two-way SyncPair |
| Filter, anonymize, or buffer events when mirroring | XCalSync |
If you’re searching specifically for “two-way sync between Google Calendar and Outlook” — the answer is XCalSync, because there is no native option. Free to try, no credit card required.
Frequently asked questions
- No. Both apps support reading the other's calendar via ICS subscription URLs, but those subscriptions are read-only on the destination side. There is no built-in option in either Google Calendar or Outlook to edit an event in one and have the change replicate to the other. True two-way sync requires a third-party tool.
- Subscribed calendars in Outlook (and Google) are intentionally read-only because the subscription is a one-way HTTP fetch of an ICS file from the source. The destination has no authenticated channel to write changes back to the source's authoritative system. Read-only is a limitation of the protocol, not a setting that can be changed.
- XCalSync runs syncs every few minutes. New events, edits, and deletions in either calendar are picked up on the next cycle. It is not literally instant, but it is far faster than the 8–24 hour delay of native ICS subscription URLs.
- No, when configured correctly. XCalSync tracks each synced event with an internal identifier so the destination event maps back to the source. Edits update the existing event rather than create a new one. Duplicates only happen if you set up two separate one-way SyncPairs in opposite directions — use a two-way SyncPair instead.
- Yes. XCalSync connects via OAuth (Google Calendar API and Microsoft Graph). It works across personal Gmail, Google Workspace, personal Outlook, and Microsoft 365 work or school. Your work IT team needs to allow third-party calendar apps via OAuth — most do.
- With two-way sync, the deletion replicates to the other calendar on the next sync cycle. If you only want one direction (e.g., deletes flow from Outlook to Google but not the reverse) you can configure a one-way SyncPair instead, or skip deletions in the sync rules.
- No. Synced events are mirrored to your destination calendar but are not re-invited to the original attendees. The attendee list is preserved as text (when supported by the source), but invitations and RSVPs only flow from the calendar where the meeting was originally created.
- Yes. XCalSync supports event filters — sync only weekdays, only events matching a name pattern, only events with specific attendees, or skip 'tentative' RSVPs. You can also rewrite event titles in the destination (e.g., replace personal event titles with 'Busy' in your work calendar).
- Yes. XCalSync's free tier covers a single SyncPair, which can be configured as two-way. Paid plans start at $4/month for two calendars or $8/month for up to ten.