You don’t usually find out you have a Microsoft 365 storage problem because something dramatic happens. A bar in the admin center quietly turns orange or red, or a new line appears on your Microsoft bill for “additional storage.”
In most tenants, that financial pressure is coming from SharePoint sites and Teams channels, while OneDrive sits in its own separate lane. Because they are often managed in the same place, it is easy to get them confused, and even easier for a "surprise" bill to show up when you aren't looking at the right bucket.
When you can’t point to any obvious change, storage feels like a cost that comes out of nowhere. The admin center shows you the number, but it doesn’t make it obvious what’s filling the pool.
Once you understand the patterns behind storage growth in Microsoft 365, the “surprise” stops being surprising. It looks like what it really is: the predictable result of how content is created, versioned, and rarely retired.
At a high level, Microsoft 365 splits your storage into two distinct buckets. It’s helpful to think of SharePoint as your company’s communal warehouse, while OneDrive operates as private lockers for individuals.
Your organization gets a base amount of storage for the tenant, plus extra storage for every qualifying license. This rolls up into the “Total storage” figure you see in the SharePoint Admin Center. Once your organization's collective usage crosses this line, you’re in paid overage territory.
According to the official SharePoint limits, the standard calculation for most Business and Enterprise plans is:
For example, a company with 100 Business Premium licenses would have a total tenant pool of 2 TB (1 TB base + [100 x 10 GB]).
Unlike SharePoint, OneDrive storage is assigned to the individual and doesn't count against your SharePoint tenant pool.
Nearly every file you interact with in Microsoft 365 lives in either a SharePoint site or a OneDrive personal site, even if the app you're using has a different name.
The storage bar in the admin center doesn’t just reflect current, active projects. It includes everything in SharePoint that lives in hot storage. That can include old project sites, personal workspaces, and content from long-departed employees.
“Hot storage” here means any content that is still active in SharePoint and therefore counts towards your tenant’s used storage. Content only stops contributing to that total when it’s moved into Microsoft 365 Archive. Until then, even inactive files, versions, and recently deleted content remain fully billable.
In most tenants, it’s not one big event that breaks the storage bank. It’s a mix of long-running patterns that never really get cleaned up.
A lot of tenants start life with a lift-and-shift from on-prem. Old file shares, project folders, and departmental drives get pushed into a handful of large SharePoint sites.
Those sites often stick around for years. The original projects are long finished, the teams have changed, and nobody feels true ownership anymore. The content is still there, it still counts against your quota, and it still sits in hot storage.
Over time, those legacy sites become migration graveyards: big, stale chunks of storage that no one wants to touch and that the platform doesn’t nudge you to review. They’re often the biggest sites in the tenant, but they’re rarely the most active.
By default, Microsoft 365 keeps a lot of versions – a default of 500 major versions for OneDrive and SharePoint. Every save is a full stored version, not just a difference. In co-authored documents, autosave and multiple people working at once stack those versions up quickly.
Big working files are the worst culprit. A weekly status deck, a long-running proposal, or a shared requirements document can accumulate hundreds of versions over its lifetime. On disk, that can translate to gigabytes of storage for a single “file.”
Lowering version limits today helps going forward, but it doesn’t solve years of existing history. That historic bloat is version debt, and it sits in the same storage pool as everything else until you actively trim it.
On the OneDrive side, storage grows in a slightly different way.
Attachments get saved “just for now,” working copies get parked in personal drives, and handoff files move between people without ever landing in a well-governed site. When someone changes roles or leaves the company, those personal workspaces often stay exactly as they were.
The result is a long tail of personal content that rarely gets reviewed, rarely gets archived, and almost never gets deleted in a structured way. It’s not obviously critical, so no one champions it, but it never leaves hot storage either.
Once the storage bar turns red, the first instinct is simple: delete a few files and watch the number go down.
In practice, that rarely works.
The files people reach for are the ones they see every day: current projects, team workspaces, shared folders. Those are usually a small fraction of your total storage.
The real bulk is in places nobody opens anymore: migration graveyards, old sites that never got a clean exit, and years of version history sitting behind a handful of living documents.
Even when teams do a big “clean out your folders” push, content doesn’t disappear right away. In SharePoint in Microsoft 365, deleted items are retained for up to 93 days, and they can continue to show up in storage used until those windows pass.
That means you can do a lot of work and see almost no movement in the admin center for weeks.
At the same time, people keep creating new content, saving new versions, and parking new working files in OneDrive.
If you only run clean-up when storage is already a problem, you’re trying to reduce a number that’s still increasing every day.
There’s also the human side. Deleting a file feels risky if you didn’t create it and don’t know who still needs it. Without clear ownership and rules, most people choose to keep things “just in case.”
That keeps you on the hook for storage, even when everyone agrees there’s too much content.
To change the cost curve, you need a way to find the heavy hitters, deal with version debt, and move genuinely inactive content out of hot storage, instead of hoping ad hoc clean-up will fix it.
If you want storage cost to stop creeping up every year, you don’t need one big clean-up project. You need to change three things that drive the math in that shared pool.
First, you have to stop creating new debt every day. That means setting sensible version limits and defaults, especially in the places where people co-author and autosave constantly.
If your environment keeps stamping hundreds of versions by default, storage will keep rising even if you run periodic clean-ups.
Second, you have to deal with the version history you already have. Lowering limits now only changes what happens going forward. It doesn’t shrink the gigabytes of history sitting behind your heaviest files.
The practical approach is targeted. Find the big offenders, trim safely, and focus on the libraries and file types that are quietly doing the most damage.
Microsoft provides capabilities that allow you to trim versions at scale, though it may take days or even weeks to implement on larger sites.
Third, you need a real way to move genuinely inactive content out of active storage without pretending deletion is the only option. That’s where archive and file-level archive come in. You keep the content available, but it stops consuming premium storage.
If you don’t change these three things, the storage bar will keep climbing. People can delete a little more, the recycle bins will churn, and you’ll still end up paying more over time because the underlying patterns never changed.
Microsoft gives you the building blocks for storage control, but Orchestry provides the control panel to actually use them at scale. Instead of a manual hunt or a complex scripting project, Orchestry streamlines the entire process.
Here’s how Orchestry helps:
Microsoft shows you totals. Orchestry helps you find what’s driving them, prioritize action, and keep the storage curve under control over time.
Storage cost surprises aren’t random. They’re the predictable result of how Microsoft 365 stores and keeps content in SharePoint and OneDrive.
If you don’t change the three levers above, you’ll keep paying more every year, even if everyone “deletes a bit more.”
Check your current storage position and trend. If the bill surprised you, the patterns above are already running in your tenant.
Orchestry helps IT and workspace owners apply lifecycle and governance standards across Teams and SharePoint, improving visibility, reducing manual work, and lowering risk as AI makes content easier to discover.
To see Orchestry in action, request a demo or download our Features Sheet to learn more.