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How to sync Outlook and Google Calendar both ways with a free app
Set up Outlook Google Calendar Sync (OGCS), a free Windows app, to keep your Outlook Calendar and Google Calendar in step in both directions. New, edited and deleted events copy across every 15 minutes, and the app runs quietly in the system tray.
By Nur Islam- 7:22 video
- 6 steps
- 8.4K views
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If you use Outlook at work and Google Calendar for everything else, you end up copying events by hand. Miss one update and you get double bookings or turn up at the wrong time.
Microsoft and Google do not offer a built-in two-way sync, so this method uses OGCS, a free open source app from GitHub. It connects to the Outlook desktop app on your PC and to your Google account, then compares the two calendars on a schedule.
You choose the sync direction, the date range, how often it runs, whether deletions carry across, and which details (location, description, attendees, colors) are copied. If you only need one direction and prefer a cloud flow, see the Power Automate videos linked in the FAQ.
What you need
- A Windows PC with the classic Outlook desktop app signed in to your account
- A Google account with Google Calendar
- The free OGCS (Outlook Google Calendar Sync) app from GitHub
Step by step
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01
Download and install OGCS
Go to the OGCS project page on GitHub (search for Outlook Google Calendar Sync) and download the installer. Double-click the setup file to install it. The app opens on the Help tab, which explains the setup process.
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02
Configure the Outlook side
Open the Settings tab. The app has a
Defaultprofile, and you can add more profiles later for other syncs.On the Outlook tab, OGCS detects the mailbox from your Outlook app. If you want to sync a shared calendar, choose the shared calendar option and pick the account. Otherwise keep your default mailbox and choose the calendar to sync from the dropdown (the video uses
Calendar).You can filter events by Outlook color category to include or exclude some of them. Leave the regional date format as default and click Test. A message showing how many calendar items it found means the Outlook connection works.
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03
Connect Google Calendar
Select the Google tab and click Retrieve Calendars. A browser tab opens. Pick your Google account, click Continue, allow the calendar permission and click Continue again. When you see the verification code message, close the browser tab.
Back in OGCS, choose the Google calendar to sync (the video uses the account's default calendar). Keep the default sync settings on this tab.
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04
Set the sync options and schedule
Open the Sync Options tab.
- Direction: choose the two-way option (the list also has Outlook to Google and Google to Outlook)
- Merge with existing entries: combines events that already exist in both calendars instead of duplicating them
- Untick Disable deletions so deleting an event in one calendar deletes it in the other
- Untick Confirm deletions so it does not ask each time
Under When, set how many days back and forward to sync (the video uses 10 days past and 60 days future) and set the interval to 15 minutes. A longer interval, like 3 hours, is fine if your calendar rarely changes.
Under What, location and description are already selected. Tick attendees if you want them copied. Color mapping matches colors to the closest option by default, and Mappings lets you set them yourself. Save the settings.
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05
Test the sync
Create an event in Outlook, then go to the Sync tab and click Start Sync so you do not have to wait for the schedule. The event appears in Google Calendar. Add an event in Google Calendar and sync again, and it appears in Outlook. Delete an event in Outlook and sync once more, and it is removed from Google Calendar.
The sync also handles recurring events and events created from meeting invites.
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06
Keep it running in the background
The app has to be running for the schedule to work. On the Application Behaviour tab, turn on:
- Start on login, so it opens when the computer starts
- Start in tray, so it runs without opening the window
- Minimise to the system tray instead of the taskbar
- Close to the system tray, so clicking the close button keeps it running
Right-click the tray icon to sync manually, switch profiles, pause or delay auto sync, or show the window.
Tips and common problems
- OGCS currently needs the classic Outlook desktop app. The developers are working on a version that does not need Outlook installed.
- Untick Disable deletions and Confirm deletions if you want deletions to carry across automatically. Leave them ticked if you are nervous about losing events.
- Turn on Merge with existing entries when both calendars already hold the same events, so you do not get duplicates.
- The sync only runs while the app is open. Set it to start on login and close to the tray.
- Use Start Sync on the Sync tab or the tray menu when you need a change to show up before the next scheduled run.
Questions
Can I sync Outlook Calendar with Google Calendar both ways for free?
Yes. Outlook Google Calendar Sync (OGCS) is a free app on GitHub that supports two-way sync, including deletions, recurring events and color categories.
Does OGCS work with New Outlook?
Not at the moment. It needs the classic Outlook desktop app on Windows. The developers are working on a version that does not rely on the Outlook app.
How often does the calendar sync run?
You choose. The video uses every 15 minutes. You can set a longer interval, or click Start Sync to run it right away.
Can I sync the calendars with Power Automate instead?
Yes, one way at a time. See the Google to Outlook flow at https://www.youtube.com/watch?v=6eC_f5PdeIE and the Outlook to Google flow at https://www.youtube.com/watch?v=33SWmcCFXNs
