Microsoft 365 storage limits in 2026: the complete reference

Microsoft 365 storage limits are documented across more than a dozen separate articles on learn.microsoft.com. Here is the consolidated reference every tenant admin should have bookmarked — grouped by workload, with the specific numbers in force in 2026 and the practical caveats behind each one.

SharePoint Online — pooled tenant storage

SharePoint storage is pooled at the tenant level and calculated as:

• Baseline: 1 TB per tenant.
• Plus: 10 GB per licensed user with a Microsoft 365 subscription that includes SharePoint.
• Example: a tenant with 500 licensed users has 1 TB + (500 × 10 GB) = 6 TB of pooled storage.

Site collection quotas default to 25 TB and can be raised to the tenant maximum. Hitting the per-site quota blocks uploads to that site; hitting the pooled tenant quota blocks new site creation and starts to throttle active sites.

OneDrive for Business — per user

OneDrive is per-user, not pooled:

• Business Basic / Business Standard: 1 TB per user.
• Business Premium: 1 TB per user.
• Microsoft 365 E3 / E5: 1 TB default; eligible for 5 TB on request to Microsoft support, and unlimited on tenants with more than 5 E3/E5 users (also requires a support ticket to enable).
• OneDrive for frontline (F1/F3): 2 GB per user.

Exchange Online — per mailbox

• Business Basic / Standard: 50 GB primary mailbox.
• Business Premium / E3 / E5: 100 GB primary mailbox.
• Shared mailbox: 50 GB (free, no licence required). To raise to 100 GB, apply an Exchange Online Plan 2 licence.
• Resource mailboxes (rooms, equipment): 50 GB.
• In-place archive: 100 GB auto-expanding to 1.5 TB on supported plans. The archive is a separate quota, invisible from the primary mailbox size.

Teams — where it actually stores files

Teams does not have its own storage pool. Everything stored "in Teams" is actually in SharePoint or OneDrive:

• Channel conversation files → the SharePoint site backing the team (counts against the pooled tenant quota).
• Private chat files → the sender's OneDrive (counts against their per-user quota).
• Teams meeting recordings → the organiser's OneDrive for private meetings; the channel SharePoint site for channel meetings.
• Teams chat text itself → stored in a hidden Exchange mailbox (SubstrateHolds), not against the pooled SharePoint quota.

Versioning defaults

Every new SharePoint document library ships with major versioning enabled and a cap of 500 versions per file. Every version stored is counted against the pooled quota.

On a 250 MB design file saved twice a day, the 500-version cap fills within a year — 500 × 250 MB = 125 GB of history for one file. This is the single largest category of silent storage growth on most tenants.

Recycle bins

• First-stage site-collection recycle bin: 93 days retention, counts against the site quota.
• Second-stage recycle bin: a further 93 days (186 days total), still counts against the site quota.
• OneDrive personal recycle bin: 93 days + 93 days for a OneDrive account whose owner is still active. For a deleted account, OneDrive is retained for 30 days by default.
• Preservation hold library (eDiscovery hold): retained indefinitely until the hold is lifted. Invisible to end users; counts against the site quota.

TSO surfaces every one of these pools in a single scan — tenant pooled quota, per-site breakdown, OneDrive per user, mailbox per user, archive per user, recycle bin per site, version history per file. The point is not to list the limits; the point is to know which one is going to break first.