Disk & Storage Guide
By To export a disk usage report, scan the drive or folder, sort the Folders view by size or open Biggest Files, then click Export and choose Save HTML report for a page anyone can open and print, or Export to CSV for rows Excel can sort. A good report names the machine, drive and date, ranks folders with a share percentage, lists the largest files with full paths and breaks space down by file type. For a PDF, open the HTML in a browser and print to PDF. WizTree and WinDirStat export CSV only. TreeSize Free saves a PDF, with Excel and HTML reserved for TreeSize Professional.
Most disk space tools are built around the moment you find the problem. The report is the moment after: a ticket that says drive D is at 96 percent and asks what is on it, a hand-over to the colleague who owns the share, a client who wants proof before approving a bigger disk. That reader was not at the scan, cannot click the treemap and needs numbers they can quote.
So the report is a different product from the scan, and the free tools treat it as an afterthought. This guide is about making one that works, in the format the reader can open, from a tool that does not charge for the export.
What Goes in a Disk Usage Report?
Start with the frame: which machine, which drive or share and when it was scanned, plus the three numbers of total, used and free space. Without those the rest floats. Then the folders ranked by size with a percentage of the total, because ten rows with a share column tell the story faster than a tree. Then the largest individual files with their full paths, since those are what someone will delete, move or archive. A path is the difference between a request and a task. Then the split by file type, which turns "the drive is full" into "the drive is 60 percent video" and points at a policy rather than a clean-up.
Leave out the noise. A list of every file on the drive is a database rather than a report. The reader will not scroll a hundred thousand rows. Cap the file list at the top fifty or hundred. If the audience is a client or an external vendor, look at the paths before sending: a folder called D:\Clients\Acme\Dispute 2025 tells them more than you meant to.
How Do I Export a Disk Usage Report as HTML or CSV?
Five steps with Univik Disk Usage Reporter, which writes both formats in its free edition. The scan is the slow part. The export takes a second.
Scan the drive or the folder the report is about
Open Univik Disk Usage Reporter and pick a drive from the home screen, or click Scan a Folder and choose the tree in question, such as a shared project folder or a user profile. A full drive scan runs in parallel and takes about a minute per terabyte. Let it finish rather than stopping early, because a report from a partial scan will show totals that do not add up to the drive's used space and someone will ask why.
Choose the view the report should lead with
The report follows the screen. For a storage clean-up, sort the Folders view by size so the top offenders are at the top. For a request to delete specific items, open Biggest Files, which gives every path. For a policy question such as whether video is the problem, use File Types. Set the sort order and any filter before exporting, since the CSV takes the rows in the order shown.
Export as HTML for reading, CSV for working
Click Export. Save HTML report writes a single self-contained page with the summary, the folder ranking and the largest files that any browser opens and prints. Export to CSV writes the current view as rows with a header line, one per folder or file, which Excel, Google Sheets and PowerShell all read. Save both when the audience is mixed: the HTML for the manager, the CSV for the person doing the deleting.
Turn the HTML into a PDF if the recipient wants one
Open the HTML file in Edge or Chrome, press Ctrl+P and choose Save as PDF or Microsoft Print to PDF. The page is laid out for A4 and Letter, so the tables break cleanly. A PDF is the safer attachment for a ticket system that strips HTML or for a client who should not be able to edit the numbers.
Name the file so it is still useful in six months
A report called report.html is useless in a folder of twenty of them. Use the computer name, the drive letter or share name and the date, for example FS01_D_2026-09-22.html. Keep the CSV beside it with the same stem. When the same drive is scanned again after a clean-up, the two CSVs can be compared in Excel to show exactly what was recovered, which is the number a manager wants to see.
HTML or CSV: Which Format for Which Reader?
HTML is for reading. It is one file, it opens in any browser on any device with no software to install, it keeps the layout with the summary at the top and the tables underneath, and it prints. Send it to the manager, attach it to the change request, drop it in the shared folder for the meeting. If the reader might edit it or the ticket system rejects HTML attachments, print it to PDF first, which takes ten seconds in Edge.
CSV is for working. It is rows and columns with no layout, which is exactly what you want when the next step is sorting, filtering, adding a column of decisions or comparing this month's scan with last month's. It opens in Excel, Google Sheets, PowerShell and any database import. Sizes come through as bytes so they sort correctly. The trade-off is that a CSV on its own does not explain itself, which is why the pairing is the answer: HTML for the person who reads, CSV for the person who acts.
We added the HTML report because support kept getting the same question from people who already had a scan: how do I show this to my boss. A CSV is not an answer to that. A page with the top folders and the biggest files, that opens on a phone, is.
What Can WizTree, WinDirStat and TreeSize Export?
WizTree exports a CSV from its File menu with every file and folder, size, allocated size, modified date and attributes. The paid edition adds a command-line switch to produce that CSV from a script. It is the most complete raw dump of the three. There is no HTML, PDF or summary output, so the reader gets a spreadsheet with hundreds of thousands of rows and has to build the picture themselves.
WinDirStat, being open source, has kept its export minimal: a CSV of the tree and that is all. People who need to show a WinDirStat result usually screenshot the treemap and type the top folders into an email. TreeSize goes the other way. TreeSize Free saves a PDF report of the current view, which is a real report, but Excel, HTML, XML and text export live in TreeSize Professional. The free build is also licensed for private use only. On a work PC that leaves the paid edition. The TreeSize and WinDirStat comparison goes into the licence detail.
Disk Usage Report Exports Compared
The question a report needs answered is whether the free build of each tool produces something you can send without reworking it.
| Question | Univik Disk Usage Reporter | WizTree | WinDirStat | TreeSize |
|---|---|---|---|---|
| Report formats | HTML and CSV | CSV | CSV | PDF free, Excel and HTML in Pro |
| Ready to read without editing | Yes, summary page with tables | No | No | PDF yes |
| Free edition can export | Yes | Yes, CSV | Yes, CSV | PDF only, private use |
| Includes largest files with paths | Yes | Yes, in the CSV | Yes, in the CSV | Yes |
| File type breakdown | Yes | Yes, in the app | Yes, in the app | Yes |
| Prints cleanly | Yes, laid out for print | No | No | Yes |
| Works on a work PC without a licence | Yes | Free for home, paid for business | Yes, open source | No, Pro needed |
Univik Disk Usage Reporter ranks folders by size, lists the biggest files with paths, tallies file types and saves the result as an HTML report or CSV from one Export menu. Free edition, no account, nothing uploaded.
Windows 7 to 11 · parallel scan · HTML report prints to PDF from any browser
The short version
- A disk usage report needs the machine, drive and date, folders ranked with a share percentage, the largest files with paths and a file type split.
- Scan, set the view and sort, then Export: Save HTML report for readers, Export to CSV for anyone who will sort or compare.
- Print the HTML to PDF in a browser when the ticket system or the client needs a fixed file.
- Name reports by machine, drive and date so two scans can be compared after a clean-up.
- WizTree and WinDirStat export CSV only. TreeSize Free saves a PDF, with Excel and HTML in the paid Professional edition.
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About This GuideLeena Taylor Paul is the author of this guide for Univik, a maker of Windows utilities since 2013. The export options for WizTree, WinDirStat and TreeSize Free were read from each tool's current menus and published documentation in September 2026. The Univik HTML and CSV exports were produced from a scan of a 2 TB data drive and opened in Edge, Excel and Google Sheets to check the layout and the byte-value sorting. 22 September 2026. Report missing a column you need? Tell support and it goes on the list.
Sources: WizTree: CSV export documentation · JAM Software: TreeSize Free · WinDirStat · Univik Disk Usage Reporter