Microsoft 365 has done a lot to improve collaboration amongst your users. With that collaboration comes a surge in Microsoft 365 data volume. And, for a lot of enterprise tenants, storage is quietly becoming a recurring cost center, and it can accelerate quickly once you cross Microsoft’s included limits.
If you don’t have a strategy, pooled storage overages (especially driven by SharePoint growth) can turn into an unplanned budget line item that compounds year after year. CrashPlan’s new Microsoft 365 Cost Savings Calculator helps you model that trajectory and quantify how archiving can help you to flatten data storage costs while also keeping your data resilient.
Why M365 pooled storage catches teams off guard
For Microsoft 365 Enterprise tenants, SharePoint Online tenant storage is calculated as:
- 1 TB base per tenant, plus
- 10 GB per licensed user
That may sound generous, until you remember two realities:
- Your pooled storage allowance grows only when you add licenses.
If headcount remains flat, your included storage will remain flat as well. Meanwhile, content continues to accumulate. - Your data doesn’t grow linearly.
CrashPlan’s calculator uses a “typical” Microsoft 365 growth rate of ~20% per year. Even if your user count grows and the environment is well managed, content sprawl, collaboration, and richer file types tend to increase volume over time.
The result: for many organizations, allowance growth cannot keep pace with data growth, and overage charges become inevitable.
Storage problems are governance problems (and SharePoint is where it hits hardest)
In most enterprises, storage overruns aren’t caused by one big thing; they’re actually caused by lots of small things:
- Redundant versions and drafts
- Orphaned Teams/SharePoint sites that never get retired
- “Just in case” retention patterns
- Obsolete or low-value content that stays hot forever
- Data that isn’t being actively used but must be retained for compliance reasons
This is why governance and storage are intertwined. Without lifecycle controls, SharePoint becomes the default long-term repository, and under Microsoft’s pooled storage structure, that can directly impact the budget.
Introducing the Microsoft 365 Cost SavingsCalculator
CrashPlan created a Microsoft 365 Cost Savings Calculator to help you connect the dots between:
- your tenant’s storage allowance,
- your actual data footprint,
- your growth rate over time,
- and the cost curve of overage fees vs. backup + archiving
Archiving lets you move inactive data to lower-cost Azure Blob Storage, freeing premium-priced M365 storage for your active data. It doesn’t impact the user experience due to file stubbing.
The calculator also makes its simplifying assumptions explicit—for example, it models Enterprise licensing, assumes 75% of SharePoint data is archivable, and uses Microsoft list pricing for excess pooled storage. If your Microsoft 365 tenant doesn’t follow these assumptions, we can walk through your unique scenario with you.
A Note: Microsoft has recently increased the price of its extra storage from $2,400 to $3,000 per TB per year, and we are hearing more reports that they are becoming less open to negotiating these prices. Even if you have negotiated a lower price in the past, it is prudent to consider the risk of significant price increases.
Two example scenarios (1,000 users)
Below are two simple models using the assumptions provided, assuming a typical data growth of 20% YoY.
Example 1: Typical data production (1,000 users)
- Exchange: 10 TB
- OneDrive: 30 TB
- SharePoint: 50 TB
- Pooled storage allowance: 10.8 TB
- Additional pooled storage required (Year 1): ~40 TB
- Cost impact (Year 1): ~$120,000/year
- Cost impact (Year 5): >$250,000/year
Using the calculator’s list-price assumption of $3,000/TB/year, the curve looks like this:
| Year | Excess pooled storage (TB) | Microsoft overage cost / year |
| 1 | 39.2 | $117,600 |
| 2 | 49.2 | $147,600 |
| 3 | 61.2 | $183,600 |
| 4 | 75.6 | $226,800 |
| 5 | 92.88 | $278,640 |
If you selectively archive (e.g., 75% of SharePoint data is archivable per the calculator assumptions), your overage exposure shrinks dramatically—because you’re removing older, colder content from Microsoft’s pooled storage. CrashPlan’s archiving feature also keeps this data accessible to users via file stubbing, so you aren’t sacrificing usability.
Example 2: Half the data usage (still 1,000 users)
- Exchange: 5 TB
- OneDrive: 15 TB
- SharePoint: 25 TB
- Pooled storage allowance: still 10.8 TB
- Additional pooled storage required (Year 1): ~15 TB
- Cost impact (Year 1): ~$45,000/year
- Cost impact (Year 5): >$115,000/year
Modeled at $3,000/TB/year:
| Year | Excess pooled storage (TB) | Microsoft overage cost / year |
| 1 | 14.2 | $42,600 |
| 2 | 19.2 | $57,600 |
| 3 | 25.2 | $75,600 |
| 4 | 32.4 | $97,200 |
| 5 | 41.04 | $123,120 |
The key takeaway: even “reasonable” SharePoint usage can become expensive when allowance is fixed and growth compounds.
Why “just buy more storage” is a bad long-term plan
Once you exceed the included pooled capacity for your tenant, Microsoft will automatically bill you for the increased amount. Nobody wants to have that uncomfortable conversation with Finance.
So you have to act, but most options come with tradeoffs:
1) Negotiate a different Microsoft deal
Sometimes possible, increasingly inconsistent, and not a strategy you can bank on every renewal, especially if list prices rise.
2) Reduce retention and delete content
This can create operational friction (“where did that file go?”) and raise compliance risk depending on your regulatory environment.
3) Move data to cold storage
It lowers costs but can be a tedious, manual process – and often makes data harder to discover and use, undermining collaboration and productivity.
4) Selectively archive with file stubbing (recommended path)
This is the “keep it usable, but stop paying premium rates forever” approach:
- Files remain visible in SharePoint
- Older/less-active data is archived based on policies you control
- When a user opens a stubbed file, it is restored automatically
Data lifecycle: why archive + backup belong together
Archiving alone can reduce Microsoft 365 storage pressure, but it doesn’t automatically give you independent recoverability.
CrashPlan’s approach is lifecycle-driven:
- Archive stale data to control active storage costs
- Backup active data to support resilience, recovery objectives, and continuity
- Together, they support compliance, recoverability, and budget predictability
CrashPlan’s calculator is built around that combined model (backup + archive), and explicitly frames the ROI as net savings + data resiliency benefits.
Try the Microsoft 365 Cost Savings Calculator to see what this looks like with your own numbers, and how quickly costs can compound over five years.
A couple of things to keep in mind as you run it:
- This calculator is intended for Enterprise tenants. If you are an Education customer, pooled storage is calculated differently; contact us, and we can run the numbers with you.
- It assumes you’re using CrashPlan for both backup and archiving, so you’re not only reducing pooled storage costs, you’re also improving data resilience.
- If you want a more precise model, complete the form on the calculator page, and CrashPlan can help you validate the assumptions against your actual tenant footprint.
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