If you are trying to overlay multiple calendars in SharePoint, you’ve probably discovered something frustrating.
Microsoft 365 does not natively support combining Outlook, Teams, SharePoint, and Planner calendars into one unified view inside SharePoint.
And yet, most organizations rely on all of them.
Let’s break down why this happens and how to solve it securely inside Microsoft 365.
Why Can’t You Overlay Multiple Calendars in SharePoint Natively?
Modern SharePoint Online is part of a service-based architecture.
Calendar data lives across multiple workloads:
– Outlook and Exchange manage mailbox calendars
– Microsoft Teams manages channel calendars
– Planner manages tasks and milestone dates
– SharePoint lists store departmental event data
– Third-party tools publish iCal feeds
These systems do not automatically aggregate into a single calendar experience inside SharePoint.
So, if you are searching:
– “How to overlay Outlook calendars in SharePoint”
– “How to combine Teams and SharePoint calendars”
– “Microsoft 365 unified calendar solution”
The short answer is: it requires either custom development or a purpose-built SharePoint calendar overlay app.
The Business Problem with Fragmented Microsoft 365 Calendars
When calendar data is fragmented:
- Events get duplicated
- Departments lose visibility into conflicts
- Communications teams rebuild consolidated views manually
- Leadership lacks a single source of truth
- Scheduling inefficiencies increase
This is not just a technical limitation. It is operational friction.
We have seen this across commercial real estate firms managing property schedules, biotech organizations coordinating research timelines, insurance companies tracking renewals, and higher education institutions juggling academic and operational calendars.
The pattern is consistent.
Everyone assumes Microsoft must have a unified calendar feature.
It does not.
Option 1: Manual Calendar Consolidation
Some organizations attempt to solve this by:
– Copying events into a “master” SharePoint list
– Using spreadsheets
– Building static dashboard views
– Maintaining separate “communications calendars”
This approach works temporarily, but it introduces duplication and ongoing maintenance overhead.
Option 2: Custom Development
It is possible to build a custom SharePoint Framework solution that queries multiple Microsoft Graph endpoints.
However, this requires:
– Ongoing maintenance
– API knowledge
– Tenant governance considerations
– Testing across multiple data sources
For most organizations, custom development is overkill for a problem that has already been solved.
Option 3: Use a SharePoint Calendar Overlay App
Cloudwell’s SharePoint Calendar Overlay app was built specifically to solve this gap inside Microsoft 365.
It aggregates events from:
- Outlook and Exchange calendars
- Microsoft Teams channel calendars
- SharePoint calendars and lists
- Microsoft Planner
- External iCal feeds
- Third-party platforms such as Asana, BambooHR, Basecamp, Canvas, Monday.com, Smartsheet, Trello, and Zoho
All inside a single, interactive interface in SharePoint and Teams.
Users can:
– Overlay multiple calendars at once
– Toggle data sources on and off
– Filter by calendar type
– Switch between month, week, and grid views
– Search across events
– Create new events directly from the interface
This creates a true Microsoft 365 unified calendar experience.
Does Cloudwell’s SharePoint Calendar Overlay App Run Inside My Tenant?
Yes.
The app is built using the SharePoint Framework and runs entirely inside your Microsoft 365 tenant.
It uses delegated Microsoft Graph permissions and does not route event data through external servers.
This makes it suitable for organizations in regulated industries where governance and compliance are critical.
Security is inherited from the Microsoft 365 platform.
What Microsoft Said About the App
During a recent product showcase, Microsoft’s Vesa Juvonen reacted to the demo by saying:
“It’s actually really cool… and looks really clean.”
He then added:
“We should have something like this in the product.”
That reaction reflects what customers experience immediately.
When multiple calendars are unified into one view, clarity improves. When clarity improves, coordination improves.
“Cloudwell’s Calendar Overlay app makes it so easy to aggregate calendars and other date-based information such as Planner tasks. Not only is it easy for end-users, it’s also very easy to administer. The ease of use was an important consideration during product comparisons since the app is so easy for any content creator to add to their SharePoint page or Team channel.”
Source: Aaron Hamilton, MarketPlace Review
Frequently Asked Questions
How do I overlay Outlook and Teams calendars in SharePoint?
Microsoft 365 does not natively support overlaying Outlook and Teams calendars inside SharePoint. A SharePoint Calendar Overlay app can aggregate these sources into one unified view.
Can I combine SharePoint lists and Outlook calendars into one calendar?
Yes. A SharePoint calendar overlay solution can pull data from SharePoint lists, Exchange calendars, Teams, Planner, and external iCal feeds into one interface.
Is there a unified Microsoft 365 calendar?
Not natively inside SharePoint. Calendar data is distributed across services. A third-party app built using the SharePoint Framework can unify them.
Is Cloudwell’s SharePoint Calendar Overlay app secure?
Yes. It runs entirely inside your Microsoft 365 tenant and uses delegated Microsoft Graph permissions. No external hosting is required.
See It in Action and Try It Yourself
Watch Cloudwell’s Calendar Overlay app demonstrated live to Vesa Juvonen in his SharePoint Partner Showcase. See how it aggregates Outlook, Teams, Planner, SharePoint, and third-party calendars into a single unified experience.
If fragmented calendars are slowing down coordination in your organization, you do not need to rebuild Microsoft 365 to fix it.
You can start by experiencing it directly.
Cloudwell’s SharePoint Calendar Overlay app is available with a 15-day free trial, allowing you to deploy it in your tenant, connect your data sources, and evaluate the unified calendar experience firsthand.
No custom development. No external infrastructure. No disruption.
Just clarity across your Microsoft 365 environment.
If you are responsible for improving visibility, reducing duplication, and strengthening coordination across teams, this is a simple place to start.