How to sync Google Calendar with Outlook (two-way or one-way)

Google Calendar and Outlook do not sync with each other on their own. You have two options:

If you only need to glance at Google events while you work in Outlook, the subscription is enough. If people book you in both calendars, you need a two-way sync, or a meeting lands on top of something the other calendar could not see.

Method 1: Two-way sync with Caltsu

Caltsu watches both calendars. When an event is added, moved or cancelled in one, it adds, moves or removes a Busy block in the other.

1. Start a trial. It runs 14 days and does not ask for a card.
2. Connect your Google account.
3. Connect your Microsoft 365 or Outlook.com account.
4. Put both calendars in one sync group.

Events in Google Calendar then show up as Busy blocks in Outlook, and Outlook events show up as Busy blocks in Google Calendar. Each block has the start and end time, the title Busy, which you can change, and a note naming the source calendar. The event title, attendees, location and notes stay in the original calendar.

If your work account is managed by an IT team, they may have to approve Caltsu first. See how to approve Caltsu in Microsoft Entra or how to allow Caltsu in Google Workspace. The Outlook integration page lists every Microsoft permission Caltsu asks for and why.

Method 2: Subscribe to Google Calendar in Outlook (one-way, free)

This shows your Google events in Outlook. Nothing flows back to Google. Microsoft documents these steps for new Outlook for Windows.

Step 1: Copy the secret iCal address

1. Open Google Calendar on a computer.
2. Open Settings, then click the calendar under "Settings for my calendars".
3. Scroll to "Integrate calendar".
4. Copy the link under "Secret address in iCal format".

Keep this link private. Anyone who has it can read the calendar. If it leaks, click Reset in the same place to get a new address and cut off the old one.

Step 2: Subscribe in Outlook

1. Open the calendar in Outlook.
2. Under the calendar grid on the left, select "Add calendar".
3. Choose "Subscribe from web".
4. Paste the link, name the calendar, for example "Google", pick a colour and select "Import".

The Google calendar now appears in Outlook. You cannot edit its events from Outlook, and events you create in Outlook do not reach Google.

In classic Outlook

Classic Outlook for Windows can import an .ics file exported from Google Calendar. Microsoft notes that an imported calendar "is a static snapshot; it does not self-update", so any change after the import has to be imported again.

Which method to pick

Pick the Caltsu sync if:

• Colleagues book you in Outlook and family or clients book you in Google Calendar, or the other way round.
• Your schedule changes during the day and both calendars need to keep up.
• The other calendar should show that you are busy, not what the meeting is.

Pick the iCal subscription if:

• You only want to see Google events while working in Outlook.
• Nobody books time in your Outlook calendar based on your Google events.

Common questions

Does Google Calendar sync with Outlook automatically?

Not both ways. An iCal subscription brings Google events into Outlook, but it is one-way and Outlook decides when to refresh it. For changes to go both ways you need a sync tool such as Caltsu.

Why are my Google events not showing up in Outlook?

With a subscription, first check that you copied the secret address in iCal format and not the public address. The public address only works if the calendar is shared publicly. If you reset the secret address in Google, the old link stops working and you have to subscribe again. New events can also take a while to appear, because Outlook refreshes subscribed calendars on its own schedule.

Can I sync Outlook to Google Calendar instead?

Yes. Caltsu syncs both directions at once, so the setup above covers it. For a free one-way route from Outlook into Google, see how to sync Google Calendar with other calendars.

Can I sync more than one Outlook or Google account?

Yes. Caltsu has no limit on connected accounts on its one plan. People who work for several clients often connect each client's Microsoft 365 account plus their own Google account. For the free options and the setup, see how to sync two Outlook calendars and how to sync two Google calendars.

Does Caltsu copy my meeting titles into the other calendar?

No. The other calendar receives the time, the word Busy or your own text, and the name of the source calendar. There is no setting that copies the title, attendees, location, notes or meeting link. Caltsu's database is in Frankfurt, Germany. See security for what it stores.