How much does Microsoft 365 Backup cost?
The list rate is $0.15 per GB per month of protected content. That sounds cheap and often isn't, because the billable total includes things most people don't count. This page is the arithmetic; how Microsoft 365 Backup pricing works covers the meter itself — what it counts, and why there is no per-seat licence to compare against.
What counts as protected content
The charge covers the user-facing size of what you protect — mailboxes, OneDrive accounts and SharePoint sites — plus online archives, plus deleted and versioned data held for recovery. The last two are the ones that surprise people. Standard usage reports don't show recycle bin contents or archive mailboxes, so a budget built from those reports alone will come in low. The PowerShell scripts for archive and deleted-item sizes pull the parts the reports omit.
Three worked examples
Each assumes a 15% version uplift on SharePoint and OneDrive — mailboxes have no file version history, so it isn't applied to them — and a recycle bin at 10% of live data across every workload. Scoped means archives excluded and sites with no activity in twelve months — 40% of SharePoint here — left out of the policy.
| Tenant | Protected | Everything | Scoped | Per user |
|---|---|---|---|---|
| 50 seats · 8 GB mailbox · no archive · 5 GB OneDrive · 150 GB SharePoint | 946 GB | $142 | $131 | $2.84 |
| 300 seats · 10 GB mailbox · 25 GB archive · 15 GB OneDrive · 800 GB SharePoint | 17.8 TB | $2,738 | $1,440 | $9.13 |
| 1,000 seats · 12 GB mailbox · 70 GB archive · 15 GB OneDrive · 4.0 TB SharePoint | 111.7 TB | $17,153 | $5,293 | $17.15 |
The archive, recycle bin and version figures above are assumptions, not measurements from anyone's tenant. Every input that moves these numbers is named in the first column, so you can reproduce any row — or change the assumptions and get your own in the calculator.
These three are single tenants. Costing a book of them is a different question, because the per-GB bill does not track headcount and the smallest client is not reliably the cheapest — the MSP portfolio view prices every client together and reports the margin on each.
When per-user pricing wins
Native per-GB pricing rewards tenants with low data per user and punishes tenants with high data per user. Third-party per-user pricing does the opposite. There is no single crossover figure, because it depends entirely on which per-user product you're comparing against. At $0.15 per GB, a $2.63 per-user product is the cheaper option once you pass about 18 GB of protected data per user; a $7.00 one not until about 47 GB. Below your own band's crossover native wins; above it, per-user does.
Protected there means after versions and recycle bin, not the live figure your usage report shows — which is the step that puts most tenants further up this curve than they expect.
The 1,000-seat row above is the clearest case. At 111.7 TB protected, native works out to $17.15 per user per month — above the top of the typical third-party band at $7.00 per user. That is driven almost entirely by the 70 GB archives.
Crossover is a price answer only. It says nothing about what native backup doesn't cover at any price, which is the half of the decision a spreadsheet won't settle.
The cheapest change is usually scoping, not switching
In the 300-seat example, excluding archives and stale sites takes the bill from $2,738 to $1,440 a month — 47% — without touching anything you'd realistically restore. Protect what you would actually recover, not everything you happen to store. That's a policy decision, not a purchase.
Costs that aren't the rate
- Growth. The invoice follows your storage curve, so model next year's volume rather than today's.
- Deleted content stays billable for its retention period, so a cleanup doesn't reduce the bill immediately.
- Native backup is billed through an Azure subscription, which some organisations don't have set up.
Scenario cost pages
Jump straight to a common tenant size: 10 users, 50 users, 100 users, 500 users, 1,000 users.
Last updated