Aggregate availability from multiple calendars

Iron Contributor

I prefer to keep personal appointments on one calendar (on and work appointments on my work calendar (O365 Exchange), but Exchange only seems to use my work calendar to show my availability to other people in my organization. I'd like to have a way to aggregate my availability from multiple calendar sources, the way that you can overlay multiple calendars in Outlook. It's not really a matter of me seeing all my appointments, because I can easily see everything in a consolidated view in Outlook on my desktop or mobile; it's more about letting others in my organization know when I'm free to meet. I know there is (used to be?) a "free/busy server" option in Outlook client, but I feel like this should be something that can be set on my Exchange profile, so that it doesn't matter what client I'm using.

Aside from that kind of option, I guess I'd guess I might be OK with a solution that duplicates anything added to my personal calendar as a block on my work calendar or vice versa, even if it's an IFTTT-type thing. I saw a similar post that mentions some 3rd-party tools from CodeTwo and Connecting Software, but given this is just a preference of mine, I'm probably not going to spend a lot on a workaround.

TLDR: Is there a better approach to showing consolidated availability than manually duplicating my appointments between calendars? Thanks!

25 Replies

Only the "primary " calendar is used indeed (you can have multiple calendar folders in the same mailbox but few/busy will only reflect the default one). So the only solution is to populate the appointments into the O365 calendar as well. As to how to do it, there are multiple methods. Adding the O365 account as an attendee is an easy solution and hardly takes more than few seconds, and you should even automate it via rules or macros. Similarly, you can get the messages directly into your O365 mailbox by configuring some form of forwarding, or using the Connected accounts functionality. Copy/pasting calendar items is also easy enough to do if you switch to a list view.

Did you ever find a better workaround for this that creating multiple appointments? I have the same issue, and for me it's not only about creating the duplicate, I don't want to see all the duplicates on my calendar view either. I looked into hiding the blocking appointments from my view (basen on subject filter), and that worked, but then I dont know if I manually blocked it (since I do not see it) and could have a mix of singles and duplicates without knowing it. An automated hidden aggregator would be the best option...

@Karim N'DIAYE 


Anyone else have a solution here? 


My problem is as follows,


"Even more important now when we are between home and the office… is the management of our calendars and availability.


Background information,

I have my main work (a***@m**.com ) calendar “Calendar” that all my meeting’s sit in, and controls my availability for “My Organization” to be able to view my busy/ free hours, when scheduling meetings.

I also have a 2x sub-calendars under this main calendar “Calendar”, called “Personal” and “Relationship” however because they are sub-calendars, they don’t merge my availability so that “My Organization” is able to view my busy/ free hours.


I like having these 3x different calendars, because I can show/hide them as I need… but of course having these sub-calendars means that I might have an appointment in “Personal” but when “My Organization” views my availability for scheduling meetings, they believe I’m free.

Therefore duplicating my meetings in my “Personal” and main “Calendar” for the same time.


Article for better explanation,


I was hoping someone would know of a better solution for this, besides manually creating blank meetings in the main “Calendar” account to block out meetings that are scheduled in my “Personal” and “Relationship” sub-calendars.


Side note,

The “Relationship” calendar is a calendar that’s shared between myself and my partner, so that if there’s a family dinner, after works drinks, or appointment that involves us both, it’s a nice way of either one of us having the option see the availability of each other.. and then of course add in a new appointment if need be :smiling_face_with_smiling_eyes: or reschedule it- if we are already doing something on that day.


Thanks in advance for any help :)"

@aco_stulic The only solution I've found so far is using a 3rd party application like Calendly to consolidate and share calendars with others. I'm still looking for a free solution, so please let me know if've you've found one since your last post. 

We have a similar issue as it relates to Microsoft Bookings. It only sees my default calendar and ignores my other calendars in Outlook even though they are shared. As a result, the Microsoft Bookings product is of little value to us as it either lacks this core functionality or is too difficult to configure as it relates to restricting availability of appointment times by cross referencing multiple calendars. Surely Microsoft can do better here.

Only adding this on the topic.


"You can connect one or Google account to your work or school account. This lets you view and manage the personal calendars in that account even when you're signed in to your work or school account. It also lets you include your personal calendar in your availability for people who are scheduling events with you."


Show personal events on your work or school calendar - Outlook (

@delvat Did Calendly let you automate the duplication of events in your 2nd calendar?

For example, if I get a meeting invite in one calendar, I want to automatically have a busy block in the other calendar.  And vice versa.



@nikbud Calendly does aggregate free/busy time but you would need a paid subscription.  At the time of this writing, one plan allows for two calendars, the next one allows up to six. 

@ChristianBergstrom This is great, but I don't have an option to add a personal calendar. I can only add a calendar "From Internet," "From Room List," "From Address Book," or "Open a Shared Calendar."

completely agree, I tried to get Microsoft bookings to work for bookable office hours as my university uses teams and office 365 for everything. But forcing me to have every event in that one calendar makes it useless. You can't filter on categories or colours, you can only turn off separate calendars and yet these extra calendars can't be used for one of the most critical aspects which is controlling your availability for meetings. I pay for a doodle service which allows bookable meetings on a webpage and can allow me to attach multiple outlook (or other) calendars to create a blocked calendar. It boggles my mind that there are so many great features in Office and yet so many bizarre ones that seem like no one uses it for real life. Great to hear others having the exact same frustration I have on this thread.

@ChristianBergstromor anyone else - do you know if it is possible to do this when you have Google's Advanced Protection enabled? It seems to be denying me for that reason.

@Greg Edwards 


For a while, I was able to get it working via, an online calendar sync application. It got the job done well.


Unfortunately my company account now has blocked access to external applications and I'm back in square one.

Did anyone find a solution? I have 2 sub calendars for groups of tasks and need them separated bc I allow others access to my appts. I dont want everyone to have access to everything.
My prob is that my teams acct only pulls information from my main calendar so I am getting double booked with meetings.. thanks

@MMreed I set up a Zap in Zapier to copy events from another calendar into my work calendar. I wanted to show my time as busy whenever there was a men's basketball game for my alma mater. So I pointed the Zap to a public calendar for the team's schedule and had it add events to my work calendar whenever a new game was posted.


The nice thing about using Zaps is that you can make the event title anything you want--have it fill in information from the other calendar directly, or call it something innocuous (like "Personal").


Here's a link to my Zap:


I've been having this issue recently, and I came across this question. After some research, I found
This tool has been working like a charm.

@Greg Edwards I haven't found a way to merge the availability across calendars. For now, I've ditched my various Outlook calendars and replaced them with the built-in Categories feature (all calendar events are within the default calendar). Although I haven't found a way to quickly show/hide calendars based on Categories, I'm questioning whether I truly need to do so.

This is great! I'm a consultant, and in addition to now being able to use Bookings, it allows me to keep client appointments confidential on my main calendar.