Your Microsoft 365 tenant gets 1 TB of SharePoint storage plus 10 GB for every license you buy. That's the whole pool. When it fills, uploads start failing and nobody can create a new site until you free space or pay for more.
Most small businesses never think about this until the day it breaks. Then it breaks on a Tuesday, mid-quarter, while someone is trying to save a proposal.
The short version:
- Your SharePoint pool is 1 TB plus 10 GB per licensed user. Nothing you do to OneDrive changes it.
- When the pool fills, uploads fail and new sites can't be created. Existing files stay readable, which is why it's slow to diagnose.
- Version history and Teams recordings are usually the culprits, and both are free to fix.
- Archive storage runs $0.05 per GB per month. Extra file storage costs more. Clean up before you buy either.
How much Microsoft 365 storage does a small business actually get?
Microsoft's own service description puts it plainly: the tenant pool is "1 TB + 10GB per license purchased" on Business Basic, Business Standard, Business Premium, E3 and E5.
Run the math for a 25-person office. That's 1 TB plus 250 GB, so 1.25 TB shared across every SharePoint site and every Teams channel's files.
A single site can hold up to 25 TB, so no one site will cap you. The pool is what runs out.
OneDrive is separate. Microsoft's limits table counts the tenant pool "not including the OneDrive created for each licensed user", so each user's OneDrive sits outside it. That surprises people who assume moving files to OneDrive solves a SharePoint problem. It doesn't — it just moves the mess.
One exception worth knowing: standalone OneDrive plans do contribute a small per-license amount to the tenant total. If you're on the usual Business or Enterprise bundles, it won't apply to you.
What breaks when the pool is full?
Uploads stop. Users get errors saving files to SharePoint and Teams, admins can't spin up new sites, and migrations halt partway through. Existing files stay readable, so it looks like a partial outage rather than a clean failure, which is why it takes a while for anyone to diagnose it correctly.
The fix is never instant either. Buying storage takes a billing change. Cleaning up takes a real look at what's in there.
What's eating the space?
Four things, in roughly this order.
- Version history. Every save of every file keeps a copy. A 40 MB CAD drawing edited 60 times is not 40 MB on disk.
- Teams meeting recordings. They land in SharePoint or OneDrive by default and nobody ever deletes them.
- The old file server. Somebody lifted twenty years of H: drive into SharePoint during a migration and kept the duplicates.
- Retention policies with no end date. If everything is retained forever, nothing gets cleaned up, by design.
Check the storage report in the SharePoint admin center before you assume anything. The site you expect to be the problem usually isn't.
Clean up before you buy
Version trimming is the highest-yield move and it costs nothing. Microsoft recommends the automatic setting, which it describes as one that "combines the data recovery benefits that version history offers while optimizing for its storage." Site admins can also queue a job to trim versions already sitting there.
Then deal with recordings. Set a retention policy that deletes Teams recordings after 60 or 90 days unless someone deliberately saves one.
One thing that won't help: emptying the site recycle bin hoping to reclaim tenant space from deleted sites. Microsoft states that "deleted sites in the Recycle Bin do not count toward the organization's total storage usage." Those bytes were already freed.
If you're deciding what's safe to delete at all, that's a retention question, not a storage question. We wrote a separate guide on what a small business should keep and for how long.
Extra File Storage or Archive: which should you buy?
You've got two paths, and they're priced very differently.
Office 365 Extra File Storage adds capacity to the pool by the gigabyte, billed monthly. Microsoft's documentation walks through buying it in the admin center and tells you to "review the pricing information before you buy more" — the rate is shown at checkout, not in the docs. Look at it before you commit, because at volume this is the expensive option.
Microsoft 365 Archive is the cheaper path for cold data. Microsoft prices archived storage at $0.05 per GB per month, charged only when your archived plus active storage goes past the quota your licenses already cover. The old reactivation fee is gone — Microsoft eliminated it on March 31, 2025, so pulling a site back out of archive costs nothing.
The catch: once you reactivate a site, you can't re-archive it for four months. Archive is for data you're confident nobody's touching, not for a site you might need next week.
Pick between them this way:
- Files people open every week — extra file storage. Archive would slow them down and the reactivation churn isn't worth it.
- Closed matters, finished projects, old clients — archive. This is exactly what $0.05 per GB is for.
- You don't know which it is — run the storage report first. Guessing here is how firms end up paying premium rates for data nobody has touched since 2019.
What we'd do for a 40-person firm
Forty licenses puts you at 1.4 TB. Here's the order of operations.
- Pull the storage report and rank sites by consumption.
- Turn on automatic version limits tenant-wide, then trim existing versions.
- Set a 90-day retention policy on Teams recordings.
- Archive any site with no activity in 12 months.
- Only then price the add-on for whatever gap is left.
Most firms that do steps one through four never reach step five. The ones that do at least know they're paying for data that earns it.
And while you're in there: SharePoint storage is not backup. Microsoft's shared responsibility model puts your data's recoverability on you, which we covered in Microsoft 365 backup and the shared responsibility model.
Frequently asked questions
Does OneDrive storage come out of the SharePoint pool?
No. Each licensed user gets their own OneDrive allocation, tracked separately from the tenant's SharePoint pool. Moving a folder from a SharePoint site to someone's OneDrive frees pool space, but it also takes that folder out of shared governance and backup scope, so it's rarely a good trade.
What counts toward the SharePoint storage pool?
Files in every SharePoint site, including the sites behind your Teams channels, plus their version history. Deleted sites sitting in the recycle bin do not count, per Microsoft's documentation. If your report looks wrong, it's usually version history, not the file count.
Can I just buy a bigger Microsoft 365 plan for more storage?
Upgrading from Business Premium to E3 doesn't change the storage math — both give 1 TB plus 10 GB per license. Adding users adds 10 GB each. If you need capacity rather than features, extra file storage or archive is the cheaper route than license upgrades.
How much warning do we get before we hit the limit?
None automatically. You have to configure it. Set storage notifications in the SharePoint admin center so owners get alerted as sites approach their limits, and check the tenant-level report quarterly. Without that, the first signal is a user who can't save a file.
Get a straight answer on your tenant
We'll pull your actual storage numbers, show you what's consuming the pool, and tell you whether you have a cleanup problem or a capacity problem. Book a complimentary IT assessment and we'll go through it with you. You can also see the full range of what we handle on our managed IT and cloud services page.
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