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How businesses can manage Microsoft 365 storage space

While Microsoft 365 users face storage limits across the platform, there are ways to increase capacity. It's also important to understand the limits in the first place.

Microsoft 365 is one of the world's most popular SaaS applications, and organizations of all sizes store vast amounts of data in its cloud. However, it is important to know the limits of Microsoft 365 storage space.

Unfortunately, Microsoft 365 storage limits are not quite as clear cut as one might expect. Microsoft 365 storage space varies widely from one subscription plan to the next and limits also vary by data type. Exchange Online, for example, has one size limit for user mailboxes and a different size limit for resource mailboxes.

Exchange Online

Organizations need to pay most attention to the Exchange Online limits associated with mailboxes because that's where the bulk of the data resides. For example, in the Office 365 Enterprise E1 plan, user mailboxes are limited to 50 GB. That limit doubles to 100 GB for those with an Enterprise E3 or E5 subscription.

Organizations with Enterprise plans also receive archive mailboxes for each user. In the case of the Enterprise E1 plan, the archive mailboxes have a 50 GB limit. Archive mailbox sizes in the Enterprise E3 and E5 plans are unlimited. However, Enterprise E3 and E5 mailboxes initially only receive 100 GB of archive mailbox space. Assuming that the business enables auto expansion, the archive mailboxes will grow to accommodate as much archive data as is necessary.

In addition, Microsoft 365 storage space is sometimes based on the presence or absence of a license. For example, shared mailboxes and resource mailboxes do not require a license, although users need a client access license to access these mailboxes. If unlicensed, however, such mailboxes are limited to 50 GB. To increase capacity to 100 GB, assign an Exchange Online Plan 2 license to a shared mailbox or an Enterprise E3 or E5 license to a resource mailbox.

SharePoint Online

There are also Microsoft 365 storage space limits that apply to SharePoint Online. However, SharePoint's limits are easier to decipher than those associated with Exchange Online. In fact, the storage limits are the same for all the Enterprise E1, E3 and E5 plans and for SharePoint Plan 1 and 2.

Microsoft 365 storage space varies widely from one subscription plan to the next.

There are site limits, but there is also a cap on the entire SharePoint deployment. SharePoint Online can accommodate up to 2 million sites or site collections (not including OneDrive). Each of these sites or site collections can hold up to 25 TB of data. Although a site can accommodate 25 TB of data, it does not mean that users have 25 TB of storage capacity.

The subscription plans include 1 TB of storage space that all of the organization's sites must share. However, Microsoft adds 10 GB of space for each user that an organization licenses. Hence, an organization that licenses 1,000 users will get an additional 10,000 GB -- or 10 TB -- of space on top of the 1 TB. Users can also purchase additional storage if necessary.


In Enterprise subscription plans, users receive 1 TB of OneDrive storage space. However, a business can increase this limit to as much as 5 TB as long as it has at least five licensed users and a qualifying plan.

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