After a merger, a joint project or just a large client on Google, your team needs to share calendars between Microsoft 365 and Google, so that everyone sees availability across two platforms. There are four ways to do it. They differ in effort, in how much people see and in how often something breaks.

Four ways to share

How calendar sync works

A sync tool copies events between the two systems. With AddSync Calendar you choose the direction for every source: Microsoft 365 to Google, Google to Microsoft 365, or both. People sign in once with their own account, after an optional email invite from the administrator.

Example: after a merger

Example, not a real customer. Two companies merge. One runs Microsoft 365 and the other Google Workspace, and the new project team of twelve people comes from both. Within a week the team has double bookings, because nobody sees the other half’s calendar.

The administrator adds the twelve people to a calendar sync and chooses two-way for the shared project calendars. The rest of both companies stay as they are. After a test week, the next team joins.

Privacy and visibility

Decide what the other side should see before you connect anyone. People are more relaxed about a shared calendar when they know the rules. One way to protect private meetings is to choose a one-way direction, so that meetings flow only from the system where they should be visible. You set the direction for every source.

Common mistakes

• Using published links for a team that needs to book across systems.
• Starting without a named master calendar.
• Connecting everyone instead of one pilot team.
• Not telling people what the other side will see.

Questions to settle first

• Who owns the master calendar?
• What should be visible to the other side?
• How do cancellations and edits travel?
• Who is the contact when something breaks?
• Which people are in the first group?

Start small

Pick one team and run a week. Create, move and cancel a few meetings in both systems and check that each side shows what you expect. Then extend to the next group. If you also run Exchange Server or HCL Domino, the same approach works for them. See the pages on Microsoft 365 sync and Gmail sync.

Which method for which team

Questions and answers

Can Microsoft 365 and Google Calendar show each other's meetings?

Yes, with a sync tool that copies events between them. Published links give a read-only view.

Do we need to change our mail systems?

No. Both platforms stay as they are. The sync works alongside them.

Can we sync one way only?

Yes. You choose the direction for every source.

How long is the trial?

AddSync Calendar has a 14-day trial.

Written by the AddSync team.