Visualization
How a Disk Space Visualizer Maps a Drive
A disk space visualizer turns folder totals into a picture. A treemap disk analyzer does that with rectangles: more bytes, more area. The drawing below is an original map of a 228 GB sample, not a screenshot of someone else's software.
Updated October 21, 2026. Windows menus can differ by version and by settings on the PC.
- Applications
- Documents
- Pictures
- Videos
- Downloads
- Backups
- System Data
Area follows the sample sizes. Color marks the category. Neither color nor corner position is a warning level.
| Category | Size | Share of sample |
|---|---|---|
| Applications | 48 GB | 21.1% |
| Documents | 12 GB | 5.3% |
| Pictures | 22 GB | 9.6% |
| Videos | 64 GB | 28.1% |
| Downloads | 18 GB | 7.9% |
| Backups | 36 GB | 15.8% |
| System Data | 28 GB | 12.3% |
Rectangle size
The layout gives each item a slice of the drawing equal to its share of the total. Videos are 64 GB of 228 GB, so that block is the largest. Documents are 12 GB, so that block is the smallest of the seven. A squarified layout tries to avoid long slivers, which means a folder can sit at the lower right without being less important than a folder at the upper left.
Folder hierarchy
Nesting means “inside.” If you could step into Videos on this sample, Project footage, Exports, and Short clips would fill that same rectangle. Their areas would be shares of Videos, not new bytes added on top of it. Parent and children are two views of one total.
Tiny files disappear for a practical reason: a pixel cannot carry a thousand labels. Zooming, or opening the folder, spends the whole canvas on a smaller total so those labels fit. The bytes were already included in the parent.
Color categories
Color on this map is a legend, not a health score. Applications are blue-tinted and Videos are teal because those categories were assigned those fills. Another tool might color by file type, by age, or by a tag a person applied. Read the legend before you read emotion into a bright block.
Reading a large block
Start with the largest rectangle and name it. On a real PC that block might be a game library, a video project, a disk image, or the Windows folder. The next question is which child holds the size. Only then is it worth asking whether those files are ones you created, ones an application cached, or ones Windows maintains.
The Windows 11 file-finding steps are the practical version of that question. The picture only tells you where to look.
Common visualization mistakes
Mistaken reading
A bright color means the folder is junk.
Clearer reading
Color follows the legend. Size follows area. Safety is a separate decision.
Mistaken reading
Two scans can be compared even if one started at C: and the other started at a user folder.
Clearer reading
Area is a share of the root you scanned. Change the root and every share changes.
Mistaken reading
The blocks must add up to the free-space number in Settings.
Clearer reading
The picture shows the sizes it was given. Cluster slack, permissions, and reserved space can leave a gap.
Mistaken reading
The largest system rectangle should be deleted because it dominates the map.
Clearer reading
Windows is large on purpose. A dominant system block is a reason to stop and identify it.
You can rehearse this reading on the interactive treemap. Click a category, check the breadcrumb, and compare the detail panel with the table above. The analyzer guide explains the scan that would produce a map like this on a real drive.