Mark Rackley recently tweeted about the ability to create a calculated column in SharePoint online document libraries that would automatically render thumbnails for documents. In the GIF from his tweet, it shows how this works for media files.
Naturally curious, I had to see how this worked for documents of .docx, .pdf, .pptx, etc. types. What I found is that it only currently supports some file types:
Supported file types (there’s likely even more I didn’t test):
- Word (.docx)
- PDF (.pdf)
- Emails (.msg)
- Images (.png, .gif, .jpg, etc.)
- Media (.mp4)
Not-yet-supported file types:
- Excel (.xlsx)
- OneNote (.one)
- PowerPoint (.pptx)
Create a thumbnail column in SharePoint Online document libraries
1. Add a new column to your document library (library settings > Create column).

2. Set the column name to Thumbnail. As for type, you have two options:
- Leave type as Single line of text. Thanks to Dario Cassinerio for sharing that Single line of text type works as well as (and more simply than) Calculated set to [Title].
- Mark Rackley suggests sticking with Calculated set to [Title] (see example screenshot) to prevent users from editing the text field in forms.

3. Click OK.
Supported file types will have thumbnails rendered (like .docx and .pdf in the example below) and others will just be blank (like .pptx and .xlsx in the example below).

Here is an animation demonstrating the entire process, start to finish using Single line of text as column type:

And another animation but using the Calculated column set to [Title] type:
