Storage & quotas in Microsoft 365

How storage works in Microsoft 365 — how much you get, what counts toward your quota, and what to do when you're running low.

Every Microsoft 365 account comes with a generous amount of storage. Understanding how it's divided — and what uses it — helps you plan ahead and avoid any surprises.

Quick summary

Each Microsoft 365 business user gets 1 TB (terabyte) of OneDrive storage for personal files. Your organization also gets a pool of SharePoint storage shared across all team sites. Email storage in Exchange (Outlook) is separate: 100 GB per user mailbox on the Microsoft 365 Business plans.

How storage is divided

Microsoft 365 storage comes in three separate buckets:

Storage type	What it's for	Typical allowance
OneDrive	Personal files, documents, photos	1 TB per user
SharePoint	Team document libraries	1 TB + 10 GB per license purchased (shared pool)
Exchange (Mailbox)	Outlook email and calendar	100 GB per user mailbox on Business Basic, Standard and Premium

These pools don't overlap — your OneDrive storage doesn't affect your mailbox, and vice versa. Your admin can set lower mailbox limits than Microsoft's maximum, either for one person or for everyone.

Checking your OneDrive storage

Open OneDrive. Sign in to Microsoft 365 with your work account, select the app launcher (the grid of dots at the top of the page), and choose OneDrive.

Look at the left-hand navigation. The Storage used link in the lower left corner shows how much you've used and how much is left. Select it to see the largest files in your OneDrive, and to empty your recycle bin.

Checking your mailbox storage

In Outlook on the web, select Settings (the gear at the top of the page), then Account → Storage. New Outlook for Windows has the same page under Settings → Accounts → Storage. You'll get a breakdown of how much space each folder is taking, with the option to permanently delete everything in a folder, or just items older than 3, 6 or 12 months.

Managing storage when you're running low

Freeing up OneDrive space

Delete old files you no longer need, then empty the Recycle Bin. Anything in your recycle bin still counts toward your OneDrive quota, and on a work or school account deleted files sit there for up to 93 days.
Remove large email attachments that have been saved to OneDrive — sometimes files are auto-saved and accumulate over time.
Archive old projects — if there are files you need to keep but won't use, consider compressing them into a zip file to reduce space.

Freeing up mailbox space

Delete emails with large attachments — these are the biggest space users. Sort by size from Filter → Sort by → Size to find them.
Empty the Deleted Items folder. Deleted Items counts toward your quota until you empty it, so deleting a message isn't enough on its own.
Use Sweep to clear out a sender in bulk — it can delete all mail from one sender, keep only their latest message, or delete anything older than 10 days. Swept items still need deleting from Deleted Items to free the space.
Move older mail to your archive mailbox, if your plan includes one.

Freeing up SharePoint space

SharePoint storage is shared across your organization. If it's running low, your admin should review which sites are using the most space and archive or clean up old content. Microsoft recommends emptying site recycle bins regularly, because what's in them counts toward the organization's total.

Getting more storage

If you genuinely need more than the included allowance, Microsoft sells storage add-ons:

OneDrive Extra Storage adds capacity for a specific person, sold in packs from 100 GB upwards and assigned to a user like any other add-on licence.
Office 365 Extra File Storage adds to your organization's shared SharePoint and OneDrive pool, in 1 GB increments.
Your admin buys these in the Microsoft 365 admin center, starting from Billing in Simplified view or the Marketplace page in Dashboard view, under the Office 365 category. Microsoft's exact steps depend on which kind of billing account you have, so follow the article below.
If you bought your subscription through a reseller or volume licensing, you can't buy Office 365 Extra File Storage from Microsoft directly — go through your partner.
If multiple people are running out, it may be worth upgrading to a plan with more included storage.

Deleting a user doesn't immediately free up their storage

When you delete a user, their OneDrive files don't disappear straight away — the default retention period is 30 days, and you should move anything you need inside it. See Removing a user safely and Transferring files when someone leaves for details.

Common questions

Do email attachments count toward OneDrive storage?

No — email attachments stored in your Outlook mailbox count toward your Exchange mailbox quota, not your OneDrive quota. However, if you save an attachment to OneDrive, it then counts toward OneDrive.

What happens if I go over my storage limit?

OneDrive: while you're over quota you can't upload, edit or sync new files, and your existing files become read-only. You can still view, download and delete them, so you can get back under the limit.

Mailbox: you'll get emails and in-app messages warning you as you get close. If you do exceed it, you won't be able to send or receive messages, and people emailing you get an error saying your mailbox is full.

The whole organization: if your tenant keeps operating above its total SharePoint storage limit, Microsoft can put the environment into read-only mode, so people can't add or change content until you free space or buy more. Files aren't deleted.

How much is 1 TB in practice?

1 TB (terabyte) is roughly a thousand gigabytes. A typical Word document is a few hundred kilobytes, so you could store an enormous number of them in 1 TB. Even with PDFs, spreadsheets, and presentations, most users won't come close. Videos take the most space — a one-hour video can be several gigabytes.

Need a hand?

If you're stuck, email support@chykalophia.com and we'll help. Include your website address and a screenshot if you can.