Microsoft's own telemetry has repeatedly shown that more than a third of sites in a mature enterprise tenant receive no file activity in any given 90-day period. Those dormant sites still consume storage quota, appear in search results, clutter permissions reports, and accumulate orphaned ownership when employees leave. Finding them is the first step to doing anything useful with them.
What "inactive" actually means in SharePoint Online
Microsoft measures activity at the site level as any file action: a view, an edit, a download, or a sharing event. A site with 10,000 documents but zero file interactions in the past 90 days counts as inactive in admin centre reporting. A site used only for its pages (viewed in the browser but with no document library interaction) may also register as inactive in file-centric usage data.
For practical governance, it helps to define two thresholds before you start the audit:
- Soft inactive: no file activity in 90 days. Flag for owner review. No action yet.
- Hard inactive: no file activity in 180 or more days, with the site owner's account disabled or no longer in the organisation. A candidate for archiving or deletion after stakeholder confirmation.
Step 1: Sort the SharePoint admin centre active sites list
The quickest starting point requires no export or scripting.
- Sign in to the Microsoft 365 admin centre and go to Admin centres > SharePoint.
- In the SharePoint admin centre, navigate to Sites > Active sites.
- Click the Last activity column header once to sort ascending. Sites with the oldest recorded activity date, or no date at all, appear at the top of the list.
- Use the Add filter button to narrow by site template if you want to review only team sites, communication sites, or project sites.
- Note the site URL, storage used (GB), and primary admin for every candidate before taking further action.
This approach works well for tenants with fewer than 200 sites. Beyond that, paging through the admin centre UI becomes slow. More importantly, the UI gives you no easy way to share the list with a manager or cross-reference against an HR system. For that, you need an export.
Step 2: Export site usage data from Microsoft 365 reports
The Microsoft 365 usage reports provide richer activity data, though they cap at a 180-day look-back window.
- In the Microsoft 365 admin centre, go to Reports > Usage.
- Select SharePoint in the left panel, then click Site usage.
- Set the date range to 180 days using the period selector at the top right.
- Click Export (the download icon) to generate a CSV. The file includes site URL, last activity date, active file count, total file count, and storage used in bytes.
- Open the CSV in Excel. Filter the Last Activity Date column for blank cells (sites with zero recorded activity in the period) or dates before your chosen threshold.
The CSV is a solid starting point for a moderate-size tenant. Its limitation is that it does not include the primary admin contact, M365 group membership, whether the site has a sensitivity label or retention hold, or the date the site was originally created. You will need to cross-reference or script those fields separately.
Step 3: Run a full site inventory with Report Master
When you need a single workbook with everything, ShareMaster's Report Master produces a full site inventory export that includes the metadata the native CSV omits.
- Open ShareMaster and authenticate with your Microsoft 365 admin account.
- Select Report Master from the tool panel.
- Choose a site inventory report and set the scope to your full tenant.
- Click Export to Excel. Report Master retrieves metadata for every site collection in the tenant and writes the results to a formatted workbook.
- In the resulting file, sort or filter on Last Activity and Storage Used. Cross-reference the Primary Admin column against your active accounts to find orphaned sites whose owners have left the organisation.
This is the recommended approach for tenants with hundreds of sites. The export is pivot-ready and can be filtered on any combination of date, owner, template, and size. For large tenants, a single Report Master run replaces several hours of manual admin centre browsing and CSV stitching.
See what a Report Master inventory export includes
Step 4: Assign a disposition to each inactive site
Identification is half the work. Once you have your shortlist, each site needs a decision. The options below cover the most common outcomes.
| Disposition | When to use it | What happens |
|---|---|---|
| Owner review | Site is recent; owner is active but usage has dropped | Email the owner. Request a response within 30 days. No structural change yet. |
| Archive | Content may be needed for compliance or future reference, but no active use | Use Microsoft 365 Archive or set the site to read-only. Storage cost is reduced. Content stays searchable and restorable. |
| Delete | No active content, no compliance hold, stakeholders have confirmed | Site moves to the SharePoint admin recycle bin. Content is recoverable for 93 days, then permanently purged. |
| Reassign | Owner has left; site content is still relevant to the team | Assign a new primary admin. Schedule a content review within 30 days of reassignment. |
| Retain and flag | Site has a compliance hold, legal matter, or retention label applied | Record the hold details in your governance log. Revisit when the hold expires. |
For sites cleared for deletion, Space Master's Bulk Delete Sites feature handles tenant-wide removal in a single operation rather than processing sites one at a time through the admin centre.
Step 5: Build a repeating review cycle
A one-time inactive site audit has a shelf life of about a month. New sites appear constantly, existing owners leave, and project teams wind down without formally closing their sites. The most efficient approach is to schedule the export as a quarterly task: run Report Master at the start of each quarter, triage results in a shared spreadsheet, and process dispositions before the next quarter begins.
Treat inactive site identification as one component of broader tenant health. For the permissions side of the same review cycle, the SharePoint permissions audit guide covers how to surface and clean up over-permissioned content at the same cadence.
Frequently Asked Questions
How does Microsoft define an inactive SharePoint site?
Microsoft's SharePoint admin centre marks a site as inactive when it has had no file activity (views, edits, downloads, or sharing events) within the chosen reporting period, which can be set to 7, 30, 90, or 180 days. Microsoft 365 also offers a built-in inactive site policy that can automatically notify owners and optionally archive sites after a configurable inactivity threshold.
Does SharePoint Online automatically delete inactive sites?
No, not by default. Without a configured inactive site policy, SharePoint Online retains site collections indefinitely regardless of activity. Microsoft 365 does send automated ownership prompts when a site's primary owner account is disabled, but that is separate from inactivity-based deletion.
What should I do with inactive SharePoint sites?
Common options include archiving the site using Microsoft 365 Archive, deleting it after confirming no active content or compliance hold exists, reassigning ownership to a current employee, or scheduling a future review. Always verify with stakeholders before deleting.
Can I automate inactive site identification in Microsoft 365?
Yes. Microsoft 365 includes an inactive site policy that can automatically notify owners and optionally archive sites after a defined inactivity period. For on-demand reporting, ShareMaster Report Master exports a full tenant site inventory to Excel in one operation, giving you a workbook you can filter on any schedule without scripting.