SharePoint Online sites draw from a shared tenant storage pool by default. Admins can cap individual sites with a manual storage limit to prevent any single site from consuming a disproportionate share of the pool. Every per-site storage setting available in the SharePoint admin centre is listed below, along with the equivalent PowerShell commands and a description of what happens when each threshold is crossed.
Per-Site Storage Settings at a Glance
| Setting | Default | Admin centre location | PowerShell parameter |
|---|---|---|---|
| Storage management mode | Automatic | Active sites > site > Storage tab | StorageQuota (set to 0 for automatic) |
| Manual storage ceiling | Not set (automatic mode) | Active sites > site > Storage tab > Manual | Set-SPOSite -StorageQuota <MB> |
| Storage alert threshold | Not configured; admin sets a percentage when switching to manual | Active sites > site > Storage tab > Alert percentage | Set-SPOSite -StorageQuotaWarningLevel <MB> |
| Alert notification recipient | Site collection administrators | Not configurable separately in admin centre; alerts go to site collection admins | No separate cmdlet; tied to site collection admin list |
| Maximum supported limit per site | 25,600 GB (25 TB) | Platform ceiling; cannot be exceeded | Maximum value for StorageQuota |
Automatic vs Manual Storage Management
In automatic mode, there is no per-site hard cap. Sites draw from the shared tenant pool and can grow until either the pool is exhausted or the 25 TB platform ceiling is reached. Storage alerts are not available in automatic mode - with no per-site ceiling, there is nothing to alert against.
In manual mode, the admin sets a specific GB ceiling. When the site crosses a configurable alert percentage, an email goes to the site collection administrators. When the site hits the ceiling, uploads and new content creation are blocked until the admin either raises the limit or the site owner frees up space.
| Characteristic | Automatic mode | Manual mode |
|---|---|---|
| Per-site hard cap | None below 25 TB platform maximum | Admin-defined ceiling in GB |
| Storage alert email | Not available | Sent when site crosses the configured alert threshold |
| Uploads blocked when limit reached | Only when the entire tenant pool is exhausted | Yes, when the site's manual ceiling is reached |
| Visibility in admin centre | Shows GB used from the shared pool | Shows GB used, the ceiling, and a percentage consumed |
| Best for | Most sites; large active collaboration sites | Sites with defined scope, client extranets, department cost accountability |
Alert Thresholds: What Triggers a Notification
| Scenario | Alert sent | Uploads blocked |
|---|---|---|
| Site on automatic management reaches high usage | No (no per-site threshold in automatic mode) | No, unless the tenant pool itself is exhausted |
| Site on manual management crosses the configured alert threshold | Yes, to site collection administrators | No; uploads continue until the hard ceiling is reached |
| Site on manual management reaches the hard ceiling | Yes, quota-exceeded notification to site collection admins | Yes; new uploads and list item creation are blocked |
| Tenant pool reaches approximately 90% capacity | Yes, to the SharePoint administrator (tenant-wide alert) | No |
| Tenant pool fully exhausted | Yes, to the SharePoint administrator | Yes; all sites in the tenant are affected simultaneously |
Admin Actions and PowerShell Reference
Common per-site storage operations using the SharePoint Online Management Shell. Storage values in PowerShell are in megabytes: multiply GB by 1,024 to convert. A 50 GB limit is 51,200 MB.
| Action | Admin centre path | PowerShell command |
|---|---|---|
| Set a 50 GB manual limit | Active sites > site > Storage > Manual > enter 50 | Set-SPOSite -Identity "https://tenant.sharepoint.com/sites/name" -StorageQuota 51200 |
| Set alert threshold at 80% of the manual limit (40 GB of a 50 GB ceiling) | Active sites > site > Storage > Alert percentage slider | Set-SPOSite -Identity "https://tenant.sharepoint.com/sites/name" -StorageQuotaWarningLevel 40960 |
| Switch a site back to automatic management | Active sites > site > Storage > Automatic | Set-SPOSite -Identity "https://tenant.sharepoint.com/sites/name" -StorageQuota 0 |
| View current storage usage for all sites | Active sites list (Storage column) | Get-SPOSite -Limit All | Select-Object Url, StorageUsageCurrent, StorageQuota |
| Find sites in manual mode using more than 80% of their allocation | Active sites > filter by storage percentage | Get-SPOSite -Limit All | Where-Object { $_.StorageQuota -gt 0 -and ($_.StorageUsageCurrent / $_.StorageQuota) -gt 0.8 } |
For context on how the per-site storage drawn by each site relates to the overall tenant pool, see the Microsoft 365 plan storage quota reference. For a breakdown of which types of content consume the most storage within a site, see what counts toward SharePoint Online storage quota.
When a site is approaching its manual limit, the fastest way to free space without buying more quota is to trim version history and reduce oversized images. ShareMaster's Space Master Version Trimmer and Image Reducer handle both operations across all libraries in a site without manual library-by-library navigation.
Frequently Asked Questions
What is the maximum storage limit for a single SharePoint Online site?
The maximum storage you can allocate to a single SharePoint Online site collection is 25 TB. In automatic management mode, a site can grow up to this ceiling or until the tenant pool is exhausted. Manual limits set by admins can be any value below the 25 TB platform maximum.
What is the difference between automatic and manual SharePoint site storage management?
Automatic storage management lets each site draw from the shared tenant pool without a per-site hard cap. Manual management sets a specific GB ceiling; when the site reaches that ceiling, uploads are blocked. Manual limits are useful for controlling storage consumption on specific sites without purchasing additional pool capacity.
How do I set a storage limit for a SharePoint site in the admin centre?
In the SharePoint admin centre, go to Sites > Active sites. Click the site's name to open its properties, then select the Storage tab. Choose Manual and enter the limit in GB. You can also configure an alert threshold percentage to receive a notification before the site reaches its ceiling.