How to Sync Multiple Calendars to Outlook

If you have multiple Microsoft and/or Google email accounts, syncing all those calendars is a crucial step to avoiding missed and conflicting meetings. To sync multiple calendars in Outlook is particularly problematic when you have one or more Google calendars and/or multiple Microsoft accounts. This article will walk you through how to get all your Office 365, Microsoft 365, Outlook.com, GSuite, and Gmail calendars synced together in Outlook so that all of your calendars reflect your true availability across all your accounts. (If you are looking how to accomplish this in Google Calendar instead of Outlook, see here)

Background and Terminology

The different flavors of Outlook, types of calendars, and methods of adding calendars to Outlook makes calendar management using Outlook surprisingly confusing and complicated. It will help to first get some background and terminology out of the way.

Don’t want to become a calendar technology expert, but still want all your calendars in Outlook? Jump to the CalendarBridge solution.

Versions of Outlook

  • Outlook for Windows – software that you install locally on your Windows machine.
  • Outlook for Mac – software that you install locally on your Mac.
  • Outlook for Android – software that you install locally on your Android device.
  • Outlook for iOS – software that you install locally on your iOS device.
  • Outlook on the Web – a web application accessed through a browser for managing professional Exchange and Exchange-Online accounts
  • Outlook.com – a web application accessed through a browser for managing personal outlook.com, hotmail.com, and msn.com accounts
  • Outlook Mobile – We use this term to refer generically to Outlook for Android and Outlook for iOS
  • Outlook – We use this term to refer generically to all versions of Outlook

Types of calendars

For the vast majority of users, there are three calendar types of interest: Microsoft (i.e,. Exchange) calendars, Google calendars, and internet calendars (iCal).

Methods of getting calendars into Outlook

  • Synced – a calendar that is synced to Outlook is one that updates in real-time as events are added, modified, and deleted. When you add an email account to Outlook and the corresponding calendar automatically comes along for the ride, that is a synced calendar.
  • Subscribed
  • Imported

Here’s how Microsoft explains the difference between subscribing and importing a calendar

When you import an .ics file, you get a snapshot of the events in the calendar at the time of import. Your calendar doesn’t refresh the imported events automatically — even if the calendar’s owner makes an update. This is a good way to add events to your existing calendar that aren’t going to change, like tide tables or phases of the moon.

Subscribing to an online calendar connects it to your calendar. Whenever the owner of a calendar you’ve subscribed to makes changes to the events, Outlook.com updates your calendar. This is a good way to track events that change frequently, like movie times or a school calendar.
Note: This update can take more than 24 hours, although updates should happen approximately every 3 hours. (link)

Since imported calendars are one-time snapshots they are not much help to those of us trying to manage multiple calendars that can change at any moment.

Likewise, subscribed calendars updating only every 3 to 24 hours means they are not reliable in preventing missed meetings and double-bookings.

This article is going to focus only on calendars that are synced to Outlook, since it is the only type of calendar in Outlook that we can truly rely on if we don’t want missed or conflicting meetings. First we will go over the free (and painful) way, and then we will go over the cheap and painless CalendarBridge way.

If you do choose the free way, there is still a cost…

Outlook’s Built-In Features for Managing Multiple Calendars Have Many Shortcomings

  1. Synced Outlook calendars are only synced to that particular instance of Outlook. If you use Outlook on multiple devices, you will have to repeat the sync setup on each of those devices.
  2. When colleagues at one of your organizations use the Outlook Scheduling Assistant, they still only see your calendar for that organization — not the other calendars you have synced in Outlook. This results in lots of meeting conflicts / double bookings.
  3. Sometimes it is not even possible to sync an account to a particular instance of Outlook due to corporate I.T. and/or data security policies.
  4. If an organization does allow syncing calendars to Outlook, typically you will have to give the organization’s IT department permission to delete everything on your device.
  5. You cannot sync a Google calendar to Outlook for Windows, Outlook on the Web, or Outlook.com (you can only import or subcribe to them).

If none of these is a showstopper for you, read the next sections on how to sync Microsoft and Google calendars to Outlook using Outlook’s built-in functionality.

If you want to save yourself time and headache, jump ahead to see how CalendarBridge syncs all your calendars into all versions of Outlook with a one-time, 5 minute setup.

Sync Multiple Microsoft/Office 365 Calendars to Outlook for Windows

Instructions for adding accounts to Outlook for Windows can be found here on Microsoft’s website. For adding Microsoft accounts, the instructions are pretty easy to follow and generally things will go smoothly. When you add a Microsoft email account to Outlook for Windows, the calendar tied to that email account is automatically syned (typically within a few minutes).

For demonstration, I have synced two different Microsoft 365 accounts from two different organizations (with domains “@exchange1” and “@exchange2”). The user can simultaneously view both calendars in side-by-side mode:

Outlook side by side calendar view
Outlook for Windows side-by-side calendar view

or click the arrow in the header of the second calendar to switch to overlay mode:

Outlook for Windows overlay calendar view

The ability to view both calendars simultaneously on the same screen is nice, but remember — these two calendars are only synced to this particular instance of Outlook for Windows. Below is what the user’s calendar looks like when logged in to Outlook on the Web using her @exchange2 credentials:

Outlook overlay calendar view
Calendars synced to Outlook for Windows are not synced in Outlook Web (or anywhere else)

As you can see, there is no trace of the events that are on her @exchange1 calendar. Importantly, this is also what her colleagues in @exchange2 see when using the Outlook Scheduling Assistant. This “blindness” of the Outlook Scheduling Assistant is why Outlook users with external calendars are constantly getting double booked. If the Outlook Scheduling Assistant is constantly double booking you, skip ahead to see how CalendarBridge will make your life easier.

Syncing Google Calendars to Outlook for Windows

As mentioned above, sadly (and somewhat mind-bogglingly, IMHO), syncing a Google email account to Outlook for Windows does NOT sync that Google account’s calendar to Outlook for Windows.

When you added a Google account to outlook for Windows, it only syncs the Google email, not the Google calendar.
Adding a Google account to Outlook for Windows adds only the email — not the calendar

If you want sync a Google calendar to Outlook for Windows for free, the solutions offered by Google and Microsoft involve jumping through some extra hoops and making some privacy sacrifices. Which hoops depends on whether you are a paying Google customer.

For free Gmail and GSuite users, the only option is to publish your calendar to an iCal (“Internet Calendar”) feed and then subscribe to that feed in Outlook for Windows. As mentioned above, iCal is not ideal at least because it can often be 3 to 24 hours out of date.

For paid GSuite users, there is the option of installing yet another piece of software: the very-descriptively-named “G Suite Sync for Microsoft Outlook (GSSMO)” tool. You can find Google’s documentation for it here.

If you take iCal or GSSMO approach, and finally get your Google calendar into Outlook for Windows, you still have to suffer with all the shortcomings listed above still apply.

If you don’t want to jump through all these hoops only to wind up with a half-solution to your calendar woes, CalendarBridge has a simpler, more-complete solution for how to sync multiple calendars to Outlook (and any other calendar app). Scroll down to see how it works.

Outlook Mobile

Unlike Outlook for Windows (discussed above), the latest version of Outlook Mobile makes syncing Google calendars just as easy as syncing Microsoft calendars. The Microsoft documentation for adding accounts on Outlook Mobile for Android is here, and for adding accounts on Outlook Mobile for iOS is here.

By default Outlook Mobile provides an overlay calendar view very similar to that provided on Outlook for Windows. But as with Outlook for Windows, Outlook Mobile simply provides a single view of multiple disparate calendars on that particular mobile device. All the shortcomings listed above still apply.

Outlook on the Web and Outlook.com

First, a note about Microsoft’s confusing branding: “Outlook on the web” refers to the web application used for accessing professional accounts hosted on an Exchange server. If the Exchange server is hosted by someone other than Microsoft, it is typically referred to as a “on-premises” Exchange server. If the Exchange server is hosted by Microsoft, it is typically referred to as “Exchange Online” or simply “Microsoft 365,” which, by the way, was recently rebranded from “Office 365,” (often shortened as “O365”). Outlook on the web does not refer to Outlook.com, which hosts personal outlook.com, hotmail.com, and msn.com accounts. Oh, and Outlook on the web used to be called Outlook Web App (OWA). Clear as mud? 😉

As of September 2018, Outlook on the Web no longer allows connecting other accounts. You can read the Microsoft announcement here.

Outlook.com does allow you to add other accounts — BUT, adding another account will not add that account’s calendar to Outlook.com (this applies to both Microsoft and Google accounts).

So, for both Outlook on the Web and Outlook.com, adding another calendar requires going the iCal route. For details on how that works (and how it often doesn’t work), check out our next article.

Update August 2020: Microsoft re-enabled the ability to connect a Google calendar to Outlook on the Web (if only they could make up their minds…). But there are a number of catches. First catch: you can only add ONE Google calendar. Second catch: the Google calendar only shows up in Outlook on the Web — it does not show up in Outlook for Windows or Outlook for Mac or Outlook Mobile. Third catch: you cannot add another Microsoft 365 / Office 365 calendar.

Sync Multiple Calendars to Outlook with CalendarBridge

As discussed above, Outlook doesn’t really sync your calendars, it just shows them all in one place. CalendarBridge, on the other hand, actually syncs all of your calendars directly on the Exchange and Google servers. So no matter which account you log into, and no matter which version of Outlook you use, all your calendars are there.

Creating your CalendarBridge account and setting up your calendar syncs takes just a couple of minutes.

Example Use Case

Let’s return to our example of the user with two Microsoft accounts and a Gmail account. Shown below is her CalendarBridge dashboard where she has added all three accounts and configured bidrectional syncs (“bridges”) between them.

CalendarBridge dashboard showing a user with two Office 365 calendars and a Google calendar.
8008800CalendarBridge Connected Accounts Dashboard

and has configured bidirectional syncs among each of the three accounts:

CalendarBridge dashboard showing sync connections established between two exchange calendars and a google calendar.
CalendarBridge Sync Connections Dashboard

Here is her @exchange1 calendar in Outlook before and after CalendarBridge:

Without CalendarBridge, times that are busy on the second Office 365 calendar are not blocked off on the first Office 365 calendar
Without CalendarBridge
With CalendarBridge, times that are busy on the office 365 calendar are blocked off on the first Office 365 calendar
With CalendarBridge

Here is what the Outlook Scheduling Assistant shows to @exchange1 users:

Without CalendarBridge, Outlook Scheduling Assistant does not account for other calendars added to Outlook
Without CalendarBridge
With CalendarBridge, all calendars are accounted for in Outlook Scheduling Assistant
With CalendarBridge

Here is her @exchange2 calendar in Outlook before and after CalendarBridge:

Without CalendarBridge, times that are busy on the first Office 365 calendar are not blocked off on the second Office 365 calendar
Without CalendarBridge
With CalendarBridge, times that are busy on the first Office 365 calendar are blocked off on the second Office 365 calendar
With CalendarBridge

Finally, here is her @gmail calendar in Google Calendar:

Without CalendarBridge, times that are busy on the Office 365 calendars are not blocked off the Google calendar.
Without CalendarBridge
With CalendarBridge, times that are busy on the Office 365 calendars are blocked off the Google calendar.
With CalendarBridge

Thus, after a single, 5-minute setup on CalendarBridge.com, all instances of Outlook — including the Outlook Scheduling Assistant — always reflect her up-to-date schedule across all of her calendars. Doesn’t that sound great? It is great. Try it now for free.

Summary

  • Outlook for PC: Syncing Microsoft calendars is easy (just add the account). Google Calendars require subscribing to an iCal feed or downloading Google’s sync tool (only for paid GSuite users)
  • Outlook Mobile: Syncing both Microsoft and Google Calendars is just a matter of adding the corresponding email accounts.
  • Outlook on the Web and Outlook.com: adding additional calendars requires subscribing to an iCal feed.
  • In all cases, an Outlook-based approach to syncing calendars has major drawbacks
  • CalendarBridge can get all your Microsoft and Google calendars into Outlook (and any other calendar app) in a single, 5-minute configuration.