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Thumbnails and preview images inside Office files: what they can show, and how to remove them

Last updated: 19 October 2026

The file's own thumbnail

The packaging format of Office files (ECMA-376 Part 2, Open Packaging Conventions) defines a thumbnail relationship: a package can point to a picture that stands for it, usually docProps/thumbnail.jpeg or a similar file. Microsoft's archived Office blog post Make your documents easier to spot with thumbnails (April 2010, written for Office 2007) describes what it is for: when you view the files in Windows Explorer or the Open dialog box with medium icons or larger, "you'll see a small picture of the beginning of your document". The post gives the switch on the Summary tab of Advanced Properties, "Save Thumbnails for All Word Documents" (or the equivalent for the program you are in), and says that "every document of that type that you save will have a thumbnail image".

For a presentation, the beginning is the first slide; for a workbook, the start of a sheet. Whatever was there when the picture was made is in it, at a small size.

When a preview can show what the document no longer does

The thumbnail is its own part of the file, not drawn from the document each time it is opened. If something changes the document without updating the thumbnail, such as a script, another program or a tool that edits the parts directly, the thumbnail stays as it was. We found no current Microsoft page that says when each version of Office redraws it, so after saving, look at the stored picture itself rather than assume it was redrawn. A first slide that was replaced, a confidential cover page that was deleted, a client's name that was edited out: the old picture can still be in the file.

Previews in other places are a separate question. We found no Microsoft or Apple page that says whether the Windows preview pane or macOS Quick Look draws its preview from this thumbnail or from the document, so do not judge a file by its preview alone.

Thumbnails inside pictures

A photo inserted into a document keeps its own data. A JPEG's Exif data can include a small thumbnail of the photo, and a JFIF header can include one too. That small picture is a second copy of the image, and it may not be the version shown on the page: a photo edited in a program that left the thumbnail alone can carry the earlier version in miniature.

The picture shown for an embedded object, such as a spreadsheet embedded in a document, is a third kind of preview. It is what the page shows, so it is visible. Whether it stays when the object is removed depends on the program and the tool; see custom XML and embedded objects.

Removing them

1. Stop saving a thumbnail. Clear the thumbnail option on the Summary tab of Advanced Properties, then save the file again. Check the result as below; the setting was described for Office 2007, and we found no current Microsoft page that says how each version treats an existing thumbnail.
2. Remove the details inside photos before you insert them, with a tool that handles that picture's format, or replace the picture with a fresh export.
3. Check the file's parts before sending, as below.

Microsoft's Document Inspector page does not mention thumbnails, so do not rely on it for them.

What ScrubDrop does with them

ScrubDrop reads .docx, .xlsx or .pptx files in your browser; the file is not uploaded. It treats the file's thumbnail as part of the document properties: the free version removes it with the author, company and the rest, from one file at a time. The data inside pictures, including their Exif and JFIF thumbnails, is picture metadata, and removing it is part of ScrubDrop Pro, for JPEG, PNG and GIF; pictures in formats it does not clean are kept as they are and listed as not checked (see the limits). When Pro removes an embedded object, it keeps the picture that was showing in Word and PowerPoint files; in an Excel workbook the object's preview picture can go with the object, so look at the result. The result is read again with separate parsers and offered only if nothing of the chosen categories remains.

How to check this yourself

1. Make a copy of the file, rename it to .zip and unzip it.
2. Open _rels/.rels and look for a relationship whose type ends in /metadata/thumbnail. Its Target is the thumbnail, usually in docProps.
3. Open that picture and look at it at full size.
4. For the photos, open the files in the media folder (word/media, xl/media or ppt/media) in a program that shows a picture's details, including any embedded thumbnail.

Questions

Sources: the Microsoft pages linked on this page were checked on 19 October 2026.