Report SharePoint Sites with File Counts and Storage Usage

SharePoint storage in Microsoft 365 is a finite, paid resource. Tenants receive a base allocation (typically 1 TB + 10 GB per licensed user) plus any add-on storage SKUs. Over time, abandoned team sites, video-heavy document libraries, and legacy migration landing zones can silently consume that pool — leading to surprise overage charges, failed uploads, and user-facing errors like Storage quota exceeded.

This recipe produces a tenant-wide inventory of every SharePoint site with two key metrics per site: item count (files and folders at the root level of the default document library) and storage used in MB. Run it as part of a quarterly capacity review, before purchasing additional SharePoint storage, or when investigating which sites are driving growth. The report is also useful during mergers, divestitures, and data-lifecycle audits where you need to justify retention or archival decisions.

What you'll have when you finish

• A sorted list of every SharePoint site in the tenant (communication sites, team sites, the root site, hub sites, and the Content Type Hub).
• Storage consumed per site in megabytes, pulled from the drive quota.used property or the root folder size.
• File/folder count at the default document library root for each site.
• A grand total of storage used across the tenant.
• Exportable CSV output for capacity planning, chargeback, or executive reporting.

Things to watch out for

• Permissions: Sites.Read.All is required to enumerate all sites. The /sites/getAllSites endpoint is inconsistent and often returns 403 — use /sites?search=* instead.
• Root-level counts only: folder.childCount at the root is not a recursive file count. Sites with nested folders will under-report unless you recurse or use the SharePoint admin Usage report.
• Quota data is eventually consistent: The quota.used value on a drive can lag by several hours. For exact chargeback numbers, cross-reference with the SharePoint admin center's Active Sites report.
• Throttling: Large tenants (1000+ sites) will hit Graph throttling (HTTP 429). Add retry-with-backoff logic and respect the Retry-After header.
• Personal OneDrive sites are excluded by the search endpoint by default. If you need them, query /users/{id}/drive separately.
• Don't modify: This is a read-only audit. Do not combine with bulk-delete operations without an explicit owner sign-off and a recycle-bin retention check.