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10 Signs Your Business Has Outgrown Its IT Setup
10 Mar, 2026
Free Tool
Email Storage Calculator
Estimate your mailbox storage requirements based on user count, email volume, retention policy, and attachment sizes — and see how it maps to Microsoft 365 limits.
Enter Your Details
e.g. info@, sales@, support@ mailboxes
Microsoft 365 Storage Limits by Plan
| Storage Feature | Basic (£4.60/user/mo) | Standard (£9.40/user/mo) | Premium (£16.60/user/mo) |
|---|---|---|---|
| Primary Mailbox | 50 GB | 50 GB | 50 GB |
| Archive Mailbox | 50 GB (auto-expanding) | 50 GB (auto-expanding) | 50 GB (auto-expanding) |
| Total per User (with archive) | 100 GB+ | 100 GB+ | 100 GB+ |
| Shared Mailbox | 50 GB (free) | 50 GB (free) | 50 GB (free) |
| OneDrive Storage | 1 TB per user | 1 TB per user | 1 TB per user |
| Max Message Size | 150 MB | 150 MB | 150 MB |
| Recoverable Items | 30 GB | 30 GB | 30 GB |
| Retention Policies | Basic | Basic | Advanced (Compliance) |
Storage limits are per Microsoft’s current allocation. Archive mailbox auto-expands beyond 50 GB for plans with Exchange Online Plan 2 or equivalent. View full Cloud Email details
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