Quick-reference numbers for the most commonly hit SharePoint Online hub site limits:
| Limit | Value | Scope |
|---|---|---|
| Maximum hub sites per tenant | 2,000 | Tenant-wide |
| Maximum associated sites per hub | 1,000 | Per hub site |
| Maximum hub hierarchy depth (officially supported) | 2 levels (root hub + one tier of child hubs) | Per hub chain |
| Hub rollup web parts: max items per render | 200 (SharePoint search query limit) | Per page render |
| Who can register a hub | SharePoint Administrator or Global Administrator | Tenant admin role required |
| Who can associate a site with a hub | Site owner of the joining site (if hub permits self-service), or SharePoint Administrator | Per-site operation |
Hub Site Hierarchy: What SharePoint Online Supports
SharePoint Online hub sites can be organised into a two-tier hierarchy. A root hub sits at the top and aggregates content from all sites connected beneath it. A child hub is a hub site that has itself been associated with the root hub; it manages its own member sites and feeds their content upward to the root hub's rollup web parts.
Regular (non-hub) sites associate with either the root hub or one of its child hubs. They are the leaf nodes of the hierarchy: content sources, not rollup destinations.
| Hub level | Can have associated sites? | Receives rollup from | Can have own branding? |
|---|---|---|---|
| Root hub | Yes (up to 1,000) | All connected member sites and child hub members throughout the chain | Yes |
| Child hub | Yes (counted within the parent hub's 1,000 limit) | Its own member sites | Yes (its theme overrides the root hub theme for its members) |
| Member site (non-hub) | No | N/A (source, not a rollup destination) | Yes (site-level branding applies within the site itself) |
Hub Registration and Association Permissions
Two separate permission levels govern hub sites. Confusing them is a common source of support tickets when site owners report they cannot join or configure a hub.
| Action | Who can perform it | Where and how |
|---|---|---|
| Register a site as a hub | SharePoint Administrator, Global Administrator | SharePoint admin center > Active sites > select site > Hub > Register as hub site. PowerShell: Register-SPOHubSite. |
| Associate a site with a hub | Site owner of the site being joined (if the hub allows self-service), or SharePoint Administrator | Site settings > Site information > Hub site association. Or admin center > Active sites > select site > Hub. PowerShell: Add-SPOHubSiteAssociation. |
| Configure hub navigation and theme | Hub site owner (Edit permissions on the hub site itself) | Navigation bar edit mode on the hub site. Site settings > Change the look. |
| Restrict who can associate sites | SharePoint Administrator | Admin center hub settings, or via PowerShell to limit association to specific users or require admin approval. |
| Unregister a hub site | SharePoint Administrator, Global Administrator | Admin center > Hub > Unregister as hub site. PowerShell: Unregister-SPOHubSite. The site itself is preserved; only the hub registration is removed. |
Hub Rollup Web Parts: Aggregation Limits
The News, Highlighted Content, and Events web parts aggregate content from associated sites at page render time. All three are powered by SharePoint search and subject to the same search query limits.
| Web part | Aggregation scope | Max items per render | Notes |
|---|---|---|---|
| News | All connected member sites (including child hub members throughout the chain) | 200 news items per query | Displays the most recent news posts. New posts appear after the SharePoint search index refreshes, typically within 15 minutes. |
| Highlighted Content | Configurable: current hub, hub and associated sites, or all sites | 200 items per query | Results reflect the search index state at render time. Newly uploaded or modified files may not appear immediately. |
| Events | All connected member sites in the hub chain | No hard documented limit; typically the next 12 upcoming events are shown | Aggregates from standard SharePoint Events lists only. Custom list templates that store event-like data are not included. |
What Happens When a Hub Site Is Deleted
Deleting a site that is registered as a hub without first unregistering it leaves all member sites with stale hub metadata. Their navigation bars and rollup connections break silently: users see no explicit error, but the hub navigation bar disappears and rollup web parts on the former hub site no longer return results. The member sites themselves are not deleted or affected in any other way.
Before deleting any site registered as a hub, follow this sequence:
- In the SharePoint admin center, select the hub site and choose Hub > Unregister as hub site. This removes the hub registration and clears the hub association from all member sites automatically.
- If member sites need to belong to a replacement hub, re-associate them before proceeding.
- Delete the former hub site only after confirming the hub relationship has been cleanly removed.
Frequently Asked Questions
How many hub sites can a SharePoint Online tenant have?
SharePoint Online supports a maximum of 2,000 hub sites per tenant, across all hub hierarchy levels combined.
How many sites can be associated with a SharePoint hub site?
Up to 1,000 sites can be associated with a single hub - both regular member sites and child hubs count toward this total. Attempting to associate a 1,001st site fails until you remove an existing association.
Can hub sites be nested in SharePoint Online?
Yes, within limits. Microsoft officially supports one nesting level: a root hub with child hubs, each of which has its own member sites. Deeper nesting creates unsupported configurations where rollup web part behaviour becomes unpredictable.
Does registering a site as a hub consume extra storage?
No. A hub registration does not consume additional storage quota. The site's content continues to count against its storage allocation in the normal way.
Can a Microsoft Teams-connected SharePoint site be a hub site?
Yes. Teams-connected sites can be registered as hubs without conflict. Hub navigation and rollup are visible when the site is accessed in a browser; they do not appear within the Microsoft Teams application.
For a complete audit of site associations across your tenant, Report Master exports site metadata including hub IDs and association status to Excel. See also the SharePoint admin roles reference for the full set of permissions required to register and manage hub sites.