How often has this happened to you?

You spent all weekend prepping for a presentation to your boss' boss. You are hyped. You’re ready to knock it out of the park. You head to the conference room you reserved specifically for this important presentation—only to find John from compliance giving his end of the year update in your meeting room!

Whoa, what just happened? Well, you just became a victim of the double-booked conference room. Here’s exactly what that means, what it costs, and what your organization can do to keep it from happening and taking profit and productivity down with it.

The Dreaded Double-Booked Meeting Room in Microsoft 365

For various reasons—not the least of which is double-booking mixups—the average meeting begins six minutes late. So when the average employee in the U.S. attends 62 meetings per month, that adds up to 6.2 wasted hours each month or 74.4 hours per employee every single year.

If you have 50 employees making about as much as the average U.S. office worker at $13.27 per hour, you’re shelling out almost $50K every single year on wasted time in meetings.

Meeting mismanagement is costly. Which is why it’s awesome that the Meeting Room integration for Outlook or Microsoft 365 makes it easy and convenient to book conference rooms.

What isn’t so awesome is one of its biggest drawbacks—the ease with which meeting rooms can be double booked. Even when a meeting planner does everything they can to be cautious, several different glitches may allow two or more parties to book the same conference room at the same time.

It’s frustrating and, above all, it’s a waste of costly real estate, valuable salary dollars, and incalculable productivity.

So can the dreaded double book be avoided? Certainly! The follow strategies and solutions will empower you to make the most of your resources and meeting rooms.

How to Prevent Double-Bookings in Microsoft 365 Calendar

As you peruse these solutions, keep in mind that many of them—such as setting to allow zero conflicts—must be implemented at the admin level. And, whenever possible, the pros and cons of each approach have been outlined so you can weigh the benefits with potential drawbacks.

Now go schedule that flawless meeting!

Disallow Recurring Bookings for All Resources

Recurring bookings sounds like a good idea, especially if you have a weekly or monthly meeting. However, using recurring bookings often allows for another party to book the room at the same time, which can create a huge headache for both groups.

Instead, you can use Set-Calendar processing to refuse recurring bookings. Microsoft goes into detail about how to implement this function here.

Of course now you can no longer book recurring meetings, which means you will need to book conference rooms for regularly-scheduled meetings manually. It's a bit cumbersome, but at least you know you'll have the room to yourself!

Set Your Allowable Meeting Conflict Rate to 0%

One of the easiest ways to prevent double bookings is to set the allowable conflict rate for meeting rooms to 0%.

This article will walk you through how to set up 0% conflict as well as adjust several other scheduling permissions.

Setting a 0% conflict will most likely prevent double books, but it can create issues if you want to set a recurring event that conflicts with an already booked room.

For example, say you want to schedule a meeting on the first Monday of each month for the next year. Zero conflict would prevent you from booking the meeting, even if the conflict is in eight months down the road. You can still easily schedule that single meeting in another location, but now you have to create it manually.

Make All Bookings Go Through a Human Gatekeeper

Another solution is to make all bookings go through a “human gatekeeper” such as a resource manager.

This tactic will help prevent most double books, but it also reduces efficiency and eliminates one of the major benefits of using Microsoft 365 to book meeting rooms—which is that it is so easy to use without any additional support.

To do this, adjust your settings so that a human “owner” has to grant permission before certain resources or rooms can be reserved.



This is a useful feature if, for example, you only have one meeting room with a smart whiteboard and want to make sure executives get priority booking. However, applying this feature to all meeting rooms creates a bottleneck in scheduling.

Create a PowerShell cmdlet That Searches for Upcoming Resource Conflicts

Another way to avoid Microsoft 365 meeting room double booking is to set up a PowerShell cmdlet that searches the calendar for double-booked meetings so one instance can be moved to an open room. This process can be complex to implement, but it certainly solves the problem.

For the uninitiated, a cmdlet is a script that performs a specific action. Sumatra Development suggests creating a script that sends both meeting owners a notification, prompting them to solve the problem themselves.

Of course, it would be far easier if Microsoft 365 simply prevented the double booking from occurring in the first place, but this at least notifies both parties of the issue before the meeting.

Now it’s up to the two parties to find a solution amongst themselves.

Set Up a Resource Mailbox to Auto Decline Double Bookings

But, what if you want to avoid forcing two meeting planners to hash out the double book issue themselves? You can create a resource mailbox for the meeting room, which essentially acts like an email address for the physical resource.

This post from Microsoft walks through how to set up a resource mailbox for a meeting room or a specific piece of equipment.

The benefit of setting up a resource mailbox is that it can be set to send automatic decline messages and it also allows admins to indicate what resources a specific meeting room has. For example, if you need a room with a projector or a specific capacity, you can easily find a room with those features.

Don’t Book Meetings as All-Day Events

Most meetings are (hopefully!) not all-day events. All-day events are generally reserved for things like birthdays, which means they default to "show time as free."

It makes sense—you want to remember that it’s Janice in payroll's birthday but you don't want to block out your calendar for the day, right?

To prevent users from booking all-day meetings (and thus creating the opportunity for double-booked rooms), limit event duration to less than 1440, which is the default maximum in Microsoft 365.



But, what if you have a remote team coming in who actually needs to book a room for the entire day? That will require creating multiple meetings for the same event, unfortunately.

Don't Make Meeting Changes Without Sending an Update Message

In a world of email overload, you might be tempted to avoid clogging coworkers’ inboxes with additional notifications. However, failing to send an update to all attendees (and resource mailboxes, if you have enabled those) can leave meetings hanging in limbo.

Sending an update helps ensure people and resources do not get double booked or 'ghost' booked, where rooms are shown as busy when they are actually available.

Avoid Using Your Mobile Device for Calendar Invitations

Make sure to only accept or decline meetings from your desktop email application. Responding to meetings from mobile apps can result in missed updates and actions may not sync correctly with your main calendar.

Cumbersome? Well, every rose has its thorns. However, this small step can prevent double-booked rooms or missing updates for canceled meetings—reducing productivity losses and frustration.

Cancel Meetings Properly

When you receive a meeting cancellation notification, make sure to click the "Remove from Calendar" button to remove the meeting from your schedule properly.

If you just delete the notification, the meeting will remain on your calendar, which can create confusion when you try to attend that canceled meeting!

The Ultimate Solution to Double Booking Rooms in Microsoft 365

One thing stands out about all the solutions above: They aren't perfect fixes.

For example, enabling 0% conflicts can make it incredibly difficult to create recurring meetings, which is a useful feature. Requiring admin approval for reserving meeting space pretty much defeats the entire purpose of using scheduling software.

So, what’s really the best solution? It might be simpler than you think.

Meeting management software created specifically to work with Outlook and Microsoft 365 can solve the dreaded double book without limiting functionality or reducing efficiency.

With AskCody, users can search for meeting rooms, set resource criteria, book catering, and much more. The best part? It utilizes your existing Microsoft and Exchange backbone, so you won't have to spend hours moving your current meetings over.

If you’re working with Microsoft 365, Outlook, Microsoft Exchange, Microsoft Teams, or Microsoft Bookings; AskCody is ready to help you take control of every dimension of the meeting experience to finally achieve everything you’ve always wanted to accomplish with your Microsoft suite.

All you have to do is download our free eBook, The Better Way to Microsoft Meeting Management, today.