What folder thumbnails are and why you'd change them
A folder thumbnail is the small preview image that appears when you look at your files in icon view. By default, Windows and Mac show you the first few files inside the folder. You can replace that with a single custom image — a photo, a solid color, or a screenshot — so you spot the folder faster and know what's inside at a glance.
Changing a thumbnail takes a few minutes and works differently on Windows and Mac. Neither method requires special software, though Windows gives you more control over what the thumbnail looks like.
Key Takeaways
- Windows lets you set a custom thumbnail by placing a file named folder.jpg inside the folder and then enabling thumbnail view in folder options.
- Mac shows the first file in a folder as its thumbnail by default, and you can't change this directly — you have to rename or reorder files inside the folder.
- On Windows, you can also right-click a folder, choose Properties, and use the Customize tab to pick a custom icon instead of a thumbnail.
- The image file you use as a thumbnail should be small (under 1 MB) and in a common format like JPG or PNG to avoid slowing down your system.
How to set a custom thumbnail on Windows
The simplest way is to place an image file named folder.jpg directly inside the folder you want to customize. Windows will use this image as the thumbnail when you switch to icon view. The image should be a JPG or PNG file, and it works best if it's square or close to square.
First, find or create the image you want to use. You can take a screenshot, read a photo, or use any image file on your computer. Rename it to folder.jpg (or folder.png if it's a PNG file). Then move or copy that file into the folder whose thumbnail you want to change.
Next, open File Explorer and navigate to the folder. Click the View tab at the top, then select Large Icons or Extra Large Icons from the Layout options. The folder's thumbnail should now show your custom image instead of the preview of files inside it. If it doesn't appear right away, press F5 to refresh the view.
If you want to hide the folder.jpg file so it doesn't clutter your folder view, right-click it, select Properties, check the Hidden checkbox, and click OK. The file will still be there and Windows will still use it as the thumbnail, but you won't see it in the folder.
How to change folder icons on Windows (an alternative to thumbnails)
If you prefer a straightforward icon instead of a photo, you can set a custom folder icon. Right-click the folder and select Properties. Click the Customize tab, then click Change Icon. A window will open showing built-in Windows icons you can choose from.
You can also use your own image file as an icon. In the Change Icon window, click Browse, navigate to an image file on your computer, and select it. Windows will convert it to an icon. This method gives you a smaller, simpler visual marker than a thumbnail, and it works in all view modes, not just icon view.
Why Mac doesn't let you change thumbnails the way Windows does
Mac's Finder automatically uses the first file in a folder as its thumbnail. You can't override this with a custom image file the way you can on Windows. Instead, you control what appears by changing what files are in the folder and in what order.
If you want a specific image to show as the folder's thumbnail, place that image file first in the folder (alphabetically or by date, depending on how Finder is sorting). You can rename the file with a number or symbol at the start — like 0_cover.jpg — to force it to the top of the list. Finder will then show that image as the thumbnail.
Using folder colors on Mac as a visual alternative
Since Mac doesn't support custom thumbnails, you can use colored folder labels instead. Right-click a folder and select a color from the menu. The folder will display with a colored dot or background, making it straightforward to spot without needing a custom image.
You can also add emoji or symbols to a folder's name to make it more visually distinctive. For example, renaming a folder to 📸 Family Photos gives you a quick visual cue without changing the thumbnail itself. This works on both Mac and Windows.
Tips for keeping custom thumbnails organized
If you use folder.jpg files on Windows, keep them small — under 1 MB — so they don't slow down your system when Windows is loading thumbnails. A 500 by 500 pixel image is usually plenty.
Use consistent image sizes and styles across folders you want to look related. If all your project folders have a similar layout or color scheme in their thumbnails, you'll find them faster when scanning a directory.
Remember that if you move a folder to a different computer or external drive, the folder.jpg file moves with it, so your custom thumbnail will travel too. If you hide the file, make sure you know it's there before you delete files from the folder.
What to do if your custom thumbnail isn't showing up
On Windows, make sure you're in icon view or large icon view. Thumbnails don't appear in list view or details view. Also check that the image file is named exactly folder.jpg or folder.png — Windows is particular about the name.
If the thumbnail still doesn't appear, try refreshing the view by pressing F5, or close and reopen File Explorer. Sometimes Windows caches the old thumbnail and needs a moment to load the new one. If you've just added the image file, wait a few seconds before refreshing.
On Mac, make sure the image file you want to use is actually the first file in the folder when sorted alphabetically. If another file comes before it, Finder will use that one instead. You can also try renaming the image file to start with a number or underscore to force it to the top.
Frequently Asked Questions
Can I use a video file as a folder thumbnail?
On Windows, the folder.jpg method only works with image files. On Mac, Finder will show a video file's thumbnail if it's the first file in the folder. Neither system will play a video as a moving thumbnail.
Will my custom thumbnail stay if I move the folder to another computer?
On Windows, yes — the folder.jpg file travels with the folder. On Mac, the thumbnail is based on the first file in the folder, so it will show whatever that file is on any computer. If you move the folder and the files inside it change order, the thumbnail may change too.
What if I want different thumbnails for the same folder on different computers?
On Windows, you can have different folder.jpg files on each computer. On Mac, you'd need to keep the files inside the folder in the same order on each computer to get the same thumbnail. This is easier to manage if you use a cloud service like iCloud Drive or OneDrive that syncs the folder across devices.
Does changing a folder thumbnail affect how the folder works or what's inside it?
No. The thumbnail is purely visual. Changing it doesn't change the folder's contents, permissions, or how programs access the files inside. You can change it back or remove the custom image anytime without affecting anything else.
Can I set a custom thumbnail for a folder on an external drive or USB stick?
Yes, on Windows. The folder.jpg file will stay on the drive and the thumbnail will appear on any Windows computer you plug it into. On Mac, the thumbnail depends on the first file in the folder, so it will work the same way on any Mac.