Google Calendar and Outlook have no built-in two-way sync. Each platform will let you subscribe to the other by URL, but that view is read-only and refreshes on the provider's schedule rather than yours. Google's own documentation says a subscribed calendar can run as much as 24 hours behind. To get edits flowing in both directions you need a third-party tool. There are four ways to do it, only three keep both calendars editable, and the right one depends mostly on whether you're willing to leave a Windows PC switched on.
Best two-way sync between Google Calendar and Outlook: SYNCDATE. Webhooks on both sides (Google push notifications and Microsoft Graph change notifications), so a change lands on the other calendar within seconds, with a 15-minute poll behind it as a safety net. Synced events show as "Busy" by default, so a work calendar never leaks personal event titles. The free tier includes real-time sync, not a trial of it. Best free option if you run Windows: OGCS — open source, actively maintained, costs nothing, but it needs a desktop Outlook install and a PC that stays on. Facts verified 2026-08-11.
Why the two don't talk to each other
Google and Microsoft are competitors, and neither has much reason to make the other's calendar work well inside its own product. Both publish perfectly good APIs; neither ships a sync.
So you get the version of the problem everyone recognises. You check Outlook before accepting a 3pm meeting and it looks clear, you say yes, and at 2:55 you remember the school pickup that lives on your personal Google Calendar. Atlassian's 2024 State of Teams report puts the share of knowledge workers juggling events across more than one calendar system at 76%, which is roughly everyone reading this.
Outlook Google Calendar sync: the four methods, ranked
Competitor facts below come from vendor pages captured on 2026-07-14: CalendarBridge pricing and help docs, the OGCS repository and wiki, and Microsoft's Power Automate pricing plus its Google Calendar connector reference. Prices move. If you're reading this a long way from that date, check the vendor before you buy.
1. SYNCDATE: if you want it to run without you
A hosted service that connects to both accounts over OAuth and listens for change notifications from Google and Microsoft directly. Nothing to install, nothing to keep running. Changes land within seconds; a poll every 15 minutes catches anything a webhook drops.
The part that matters more than speed for most people: synced copies show as "Busy" with no title unless you turn detail-copying on. Your employer's calendar sees that you're unavailable at 4pm on Thursday, not that it's a therapy appointment.
Beyond Google and Outlook it also handles iCloud, Fastmail and Nextcloud over CalDAV, and read-only iCal feeds as one-way sources. Hosted in Germany, tokens encrypted at rest.
2. OGCS: if you're on Windows and want it free
Outlook Google Calendar Sync is an open-source Windows application under MPL-2.0. It does genuine two-way sync between Outlook and Google, it costs nothing, and it's under active development: the most recent release at the time of the July capture was v3.0.3 Alpha on 2026-07-12, with v2.12.0 Beta as the current stable. Worth knowing while you search, because it trips people up: that name belongs to this one program rather than to the category, so plenty of results for it are about OGCS specifically and not about connecting the two calendars generally.
The catch is architectural, not a quality problem. OGCS runs on your desktop and drives a desktop Outlook install, so sync happens when your PC is awake and stops when it isn't. Scheduled syncs are also capped: the project's FAQ sets a 15-minute floor, or 120 minutes with Push Sync enabled, described as fair use against the shared Google API quota. Push Sync fires within two minutes of a change made in Outlook, but only in that direction.
If you're a Windows user at a desk, that's a genuinely good deal. On a Mac, a Chromebook, or a phone, it isn't an option at all.
3. CalendarBridge: if you also want scheduling pages
A hosted competitor covering Google, Microsoft 365 business, personal Microsoft accounts, iCloud, and other calendars via .ics link. Their pricing page describes sync as typically updating in under a minute for Google and Outlook, and every 5 to 10 minutes for iCloud and .ics sources. Scheduling pages and a unified calendar app come bundled on every tier.
Two things to know before you commit. There's no free tier, only a trial whose length isn't published anywhere on their site. And the top plan tops out at 8 calendars, so if you're already past that, the purchase you're planning doesn't exist.
Credit where it's due on the thing we used to get wrong about them: disconnect a sync and CalendarBridge removes the event copies it created.
4. Native ICS subscription: only if read-only is genuinely enough
Free, built in, and one-way. Publish one calendar as an ICS URL, subscribe to it from the other, and you get a view. You can't edit through it, and refresh is on the provider's clock, which Google documents as up to 24 hours and Microsoft doesn't commit to at all.
Worth using for a calendar you only ever need to look at. Useless for the double-booking problem, because a scheduling tool reading your Outlook availability won't reliably see subscribed events.
Side by side
| SYNCDATE | OGCS | CalendarBridge | ICS subscription | |
|---|---|---|---|---|
| Direction | Two-way | Two-way | Two-way | One-way, read-only |
| Typical delay | Seconds (webhooks both sides) | 15-min scheduled floor; Push Sync within 2 min, Outlook-side only | Vendor claims under a minute for Google/Outlook | Up to 24 hours |
| Runs where | Hosted | Your Windows PC, desktop Outlook required | Hosted | Provider-side |
| Other providers | iCloud, Fastmail, Nextcloud (CalDAV); iCal feeds | Google and Outlook only | iCloud, plus .ics links | Anything with an ICS URL |
| Calendar ceiling | 100 on Pro | None stated | 8 on Pro | N/A |
| Free option | Yes, includes real-time sync | Yes, entirely | No, trial only, length unpublished | Yes |
| Price | Free, then see pricing | Free | $5/mo, $4 billed annually, up to $40/mo ($32 annually) | Free |
Microsoft's Power Automate is a fifth route worth naming and not ranking, because it's a build rather than a setup. The Google Calendar connector is real and Microsoft-published, but two-way sync means authoring a flow per direction plus your own deduplication and conflict handling, and the connector's documented trigger poll is one per 90 seconds. Standalone it's Power Automate Premium at $15.00 per user per month paid yearly. Microsoft 365 Business Basic ($7.00 per user per month, paid yearly) bundles a narrower SKU that the compare matrix limits to cloud flows only, so treat "it's included with my 365 plan" as something to check rather than assume.
How the sync actually works
Worth understanding because it explains the speed difference, and because it tells you what breaks when something breaks.
Google and Microsoft both offer change notifications: tell them where to send a ping, and they ping you when a calendar changes. SYNCDATE subscribes to both, so a webhook arrives within a second or so of the edit. It then fetches only what changed, using sync tokens on Google and delta queries on Microsoft, rather than re-reading the whole calendar.
Before writing anything, it checks whether the incoming event is a copy it made earlier. Every synced event carries an identifier in its metadata; if that's present, the change is dropped. Skip that step and you get an infinite loop, where A copies to B, B's new event looks like a change, and it copies back to A forever. Anyone who has built calendar automation by hand has met this bug.
The write goes to the target calendar, and a poll every 15 minutes sweeps up anything a dropped webhook missed. Deeper version: how calendar sync actually works.
Set up Google Calendar and Outlook sync in 4 steps
1Sign in with your Google account
Go to syncdate.app and click "Get Started." Sign in with Google. This runs over OAuth 2.0, so no password is ever seen or stored, and only calendar permissions are requested.
You'll need a Google account, a Microsoft Outlook or Microsoft 365 account, and about five minutes.
2Connect your Outlook account
From the dashboard, click "Add Account" and pick "Microsoft Outlook." Microsoft's own login page handles the rest, using its OAuth 2.0 flow. Personal Outlook.com, Hotmail, work and school accounts all work.
If your workplace runs Microsoft Entra ID, you may hit a "Need admin approval" screen. That's your organisation's policy rather than an error; the troubleshooting section below covers what to do about it.
3Create the sync
Click "Create Sync" and pick the Google calendar and the Outlook calendar you want connected. Then choose the direction: two-way keeps both editable and in step, which is what most people want for a work and personal pair. One-way pushes from source to target and ignores edits coming back, which suits broadcasting a calendar you don't want anyone changing.
Events copy across as "Busy" with no title by default. If you want real titles on one side, change it here rather than assuming.
4Test it, then forget about it
Sync starts immediately. Create a throwaway event on one calendar and watch it appear on the other, usually before you've switched tabs. Delete it, and watch the copy go too.
That last part is the test people skip and then worry about later: deletions propagate, and removing a sync can clean up everything it created.
What crosses over, and what doesn't
| Property | Synced? | Notes |
|---|---|---|
| Event title | Yes | Subject to your privacy setting; "Busy" by default |
| Date and time | Yes | Converted between provider timezone formats |
| Duration | Yes | |
| Recurrence | Yes | Synced as a series with its RFC 5545 RRULE, not as individual copies |
| Description | Yes | |
| Location | Yes | |
| Attendees | Optional, off by default | Two modes: a plain-text guest list added to the description, or real invitees. The second makes external guests see the copy as a second invitation, which is why it's off unless you turn it on |
| Busy/free status | Yes | |
| All-day events | Yes | |
| Reminders | No | Each provider runs its own reminder system |
| Calendar colour | Yes, approximately | Snapped to the nearest match in the destination provider's palette |
| Attachments | No | |
| Categories and tags | No | Google and Outlook model these differently |
Timezones
Google uses IANA identifiers like America/New_York. Outlook uses Windows identifiers like Eastern Standard Time. These are converted on the way through, so events land at the correct local time on both sides.
Recurring events are the fussy case, because Google requires explicit timezone information on the start and end of a series while Outlook sometimes carries floating times. That gets resolved before the write rather than left to the destination to guess.
All-day events
Google represents an all-day event as a date with no time. Outlook represents it as midnight to midnight in a specific timezone. Handled correctly, you get a full-day event on the other side; handled naively, you get a meeting that starts at 00:00 and a reader who thinks the sync is broken.
When it doesn't work
"Need admin approval" on the Microsoft side
If your Outlook account belongs to an organisation, Microsoft Entra ID decides which third-party apps may touch its data, and the default for many tenants is no. Ask IT to approve SYNCDATE in the Entra admin center, or connect a personal Outlook.com account instead, which needs no approval.
This is the single most common reason a setup stops dead, and it isn't something a sync tool can work around. Nor should it be able to.
Google Workspace blocking it
Some Workspace domains restrict third-party API access under Security → API Controls in the admin console. Same shape of fix: an admin adds an allow-list entry, or you connect a personal Gmail account.
Sync worked, then stopped
Usually an expired OAuth token that couldn't refresh itself. Check the dashboard for an error flag, then reconnect the affected account under Accounts → Reconnect. Reconnecting refreshes the credential without touching your sync configuration.
Duplicate events everywhere
Nearly always a second copy mechanism running alongside the first, most often an old ICS subscription between the same two calendars that never got removed. Delete the subscription. More on the general case: how to stop calendar events duplicating.
What the free tier does, and what it doesn't
Free covers real-time two-way sync between one Google calendar and one Outlook calendar, with "Busy" privacy on by default. That's the actual job rather than a demo of it, there's no card, and it doesn't expire.
What it doesn't cover, said plainly here because finding out in month two is worse. It's one sync process, so a third calendar means a paid plan. The forward window is 30 days, which means an event you book in January for March won't copy across until March comes into range, and people do get caught by this. And copies carry a small SYNCDATE tag that only paid plans remove.
Plus raises the window to a year and lifts the tag; Pro removes the window entirely and adds per-calendar settings, which is what you need if you want full detail flowing one way and "Busy" coming back the other. Current limits and prices live on the pricing page, never in this article, because a number typed into a blog post outlives the price it described.
If iCloud is in the mix alongside Google and Outlook, syncing all three in one tool covers that setup. For a two-way pairing specifically, two-way sync between Outlook and Google Calendar goes deeper on direction and loop prevention. And the full tool comparison covers the wider market.
Frequently Asked Questions
Can Google Calendar and Outlook sync automatically?
Not on their own. Neither Google nor Microsoft ships a two-way sync with the other, and the built-in ICS subscription each offers is read-only and can lag up to 24 hours. Automatic two-way sync needs a third-party tool: SYNCDATE (hosted, within seconds via Google push notifications and Microsoft Graph change notifications), OGCS (free, Windows desktop only), or CalendarBridge (hosted, no free tier).
What is the fastest way to sync Outlook and Google Calendar?
Webhook-driven services are the fastest, because they react to a change notification instead of asking on a timer. SYNCDATE propagates a change within seconds. For comparison, Microsoft documents its Google Calendar connector trigger as polling once per 90 seconds, OGCS sets a 15-minute floor on scheduled syncs, and an ICS subscription refreshes on a schedule the provider controls. The gap matters because until a change lands, your calendar is advertising availability you no longer have.
Is it safe to give a third-party app access to my calendar?
It depends entirely on how access is granted and what the app does with it. Look for OAuth 2.0, which means you sign in with Google and Microsoft directly and the app never sees your password, and check that you can revoke it yourself (via Google Account permissions or Microsoft account permissions) without asking anyone. SYNCDATE encrypts stored tokens with AES-256-GCM and runs in the EU. Longer version: is it safe to give apps access to your Google Calendar.
Does this work with Microsoft 365 and Outlook 365?
Yes. Sync runs against the Microsoft Graph API, which is the cloud calendar behind every Outlook surface, so personal Outlook.com, Microsoft 365 business and enterprise accounts all work the same way. One caveat for work accounts: an Entra ID administrator may need to approve the app before you can connect it.
Will synced events show up in the Outlook desktop app?
Yes. Because the sync writes through the Microsoft Graph API rather than into a local file, events appear in Outlook on the web, the desktop app, and Outlook mobile, anything signed into that Microsoft account. This is the main practical difference from OGCS, which drives a desktop Outlook install directly and needs that machine running.
How do I sync my work Outlook calendar with my personal Google Calendar without sharing details?
This is the default setup, not an advanced one. Connect both accounts, create a two-way sync between the two calendars, and leave the privacy setting alone: copies appear as "Busy" with no title, location or description. Your colleagues see when you're unavailable and nothing else. If you want detail flowing one direction and "Busy" the other, that's an asymmetric setup and needs a Pro plan.
Can I sync more than one Google calendar with Outlook?
Yes, by creating a sync for each pairing. The free plan covers one sync across two calendars, so multiple calendars means a paid plan; see current pricing for the limits on each. Once you're past three or four calendars, the hub-and-spoke pattern keeps the number of syncs down considerably compared with connecting everything to everything.
What happens if I edit the same event in both calendars at once?
Last write wins, judged on the event's updated timestamp, so the more recent edit overwrites the older one. In practice this is rare, because a four-second propagation window means the first edit has usually already landed on the other side before you make the second.