File-Type Breakdown

3 min read

The File-Type Breakdown is SharePoint Storage Explorer's "what is my storage made of?" view. Rather than ranking individual files or sites, it groups every scanned file by extension and shows you how much storage each type contributes.

Where to find it

Click the Overview tab in the left navigation. The File-Type Breakdown is the second panel on that page (the first is the tenant total). It draws on data from your most recent deep scan — see light vs deep scan.

What the view shows

A bar chart and table of file extensions with columns for:

Extension — .pdf, .pptx, .mp4, etc.
File count — how many files of this type exist tenant-wide.
Total size — sum of all files of this type.
Average size — total divided by count.
% of tenant — what fraction of tenant storage this type accounts for.

Sort by Total size descending to see the biggest contributors at the top.

Common findings

Most tenants show one of a few familiar patterns:

PowerPoint dominance — .pptx files account for 20-40% of storage. Often driven by image-heavy decks that nobody opens after the meeting.
Video bloat — .mp4, .mov, .wmv collectively account for double-digit percentages, often from training recordings or marketing assets uploaded as a one-off.
Outlook archives — .pst or .msg files in single-digit percentages but very large per-file size. Usually individual users' email exports that should live in their mailbox or in a dedicated archive product like Chipmunk, not in SharePoint.
Bulk media — .psd, .ai, .raw, .tif from design teams. Large per-file, usually a small absolute count but a meaningful fraction of total storage.
Backups and disk images — .iso, .vhd, .vmdk, .bak. Should almost never be in SharePoint; usually accidental uploads.
Long-tail — the bottom 100+ extensions each contribute fractions of a percent and collectively account for under 5%.

What to do with the findings

For each meaningful contributor:

Is this content people use? Check the file-type's average modified date. Old, unused files are archive candidates for Squirrel.
Is SharePoint the right home? Video and large media often belong on Stream, Azure Blob, or a CDN; Outlook archives belong in mailbox archive systems; backups belong in a backup product.
Are there per-site patterns? Combine with site overview — if one site is contributing most of a file type, talk to its owner directly.

Exporting

The Export button in the top action bar produces a CSV of every extension with all four columns, ready to pivot in Excel or use in a board paper.

When extensions look unfamiliar

You may see extensions that are SharePoint-internal (.aspx, .xsn, .dwp) or content-type artefacts. These are usually small in aggregate and not worth investigating unless they appear at the top of the list, in which case it usually indicates a site template or workflow that is generating an unusual volume of system content.