How do I change the thumbnail of an MP4?
Open the file, go to Cover art in Edit & clean and choose Use current frame or Choose image. The new picture replaces any cover art the file already has when you press Download new file.
Free · runs in your browser
Add a thumbnail to an MP4 file
Pick the perfect frame or your own image and embed it as cover art, so file browsers and media libraries show it instead of a random first frame.
To add a thumbnail to an MP4, open the video here, find the frame you want, and in Edit & clean under Cover art press Use current frame, or Choose image to use a picture of your own. Then press Download new file. The image is stored inside the MP4 as cover art, and the video itself is not touched.
That embedded image is what Windows File Explorer and iTunes-style media libraries can show in place of the frame they would otherwise pick. It is not what YouTube, Instagram or a web page shows: those use their own thumbnail settings, covered below so you put the effort in the right place.
It works in your browser, on a phone or a computer, and the file is never uploaded. Cover art is part of MP4 and MOV only; for other edits to the same file, see the MP4 metadata editor.
How to add a thumbnail to an MP4
Open the MP4
Press Open a file (Ctrl/Cmd+O) or drop the file on the page. MP4, MOV and M4V files can take cover art.
Find the frame
Go to the moment you want. The Frames section has a filmstrip to help you choose; Save frame keeps a PNG copy if you want to edit it first.
Set the cover art
In Edit & clean, under Cover art, press Use current frame, or Choose image for a JPEG or PNG of your own. Remove cover art clears an old one.
Download the new MP4
Press Download new file (Ctrl/Cmd+S). What changed confirms the cover art was added; the video and audio are copied unchanged.
Three different things called a “thumbnail”
Most confusion about MP4 thumbnails comes from mixing up three separate things. Only the first is stored in the file.
- Embedded cover art. An image inside the MP4’s metadata, in the iTunes-style
covratom (or Apple’s artwork key). This is what this page adds. It travels with the file. - A generated preview. File managers and galleries make their own small picture from a frame, usually near the start, when there is no cover art or when they ignore it. It is stored on your computer, not in the file.
- A platform thumbnail. YouTube, Vimeo, Instagram and TikTok each make or let you choose a thumbnail when you post. It lives on their servers and has nothing to do with what is embedded.
Where the embedded thumbnail shows up
Support for cover art varies between apps and even between versions of the same app, so treat this as a guide and check on the device that matters to you.
| Where | Uses embedded cover art? | Notes |
|---|---|---|
| Windows File Explorer | Usually, in icon and tile views | Thumbnails are cached; an old preview can linger until the cache refreshes |
| Apple TV app and iTunes-style libraries | Usually | The main reason M4V files carry artwork |
| Media servers (Plex, Jellyfin, Kodi) | Sometimes | Most prefer posters from online data or an image file next to the video |
| Android galleries and players | Some do | Many generate a frame instead |
| Web pages | No | A web player shows its own poster image or the first frame |
| YouTube | No | Choose a custom thumbnail in YouTube Studio |
| Instagram, TikTok, WhatsApp | No | The app picks a frame or lets you choose a cover when you post |
If Explorer keeps showing the old picture, make sure you are looking at the downloaded copy, then switch to another view and back. Windows’ Disk Cleanup can also clear its thumbnail cache.
Choosing a good cover
From the video
A frame from the clip itself is honest and matches the content. Pick a still moment with a clear subject: motion blur and half-closed eyes look worse at icon size than in playback. Use current frame takes the frame you are on. If your browser cannot decode the video (some HEVC or ProRes files), use Choose image with a screenshot or a still exported elsewhere.
From an image
- Use a JPEG or PNG. A picture with the same shape as the video (16:9 for most landscape clips, 9:16 for phone portrait videos) avoids awkward cropping in file browsers.
- Large text survives being shrunk to an icon; small captions do not.
- The image adds its own size to the file, so a huge photo makes the MP4 larger by the same amount. A picture a few hundred kilobytes in size is plenty.
MP4 and MOV only
Cover art is part of the MP4 family (MP4, MOV, M4V, 3GP), and that is where this tool writes it. MKV handles images differently, as file attachments, and AVI and MPEG-TS have no place for one; the option is switched off for those files.
Writing the cover is a metadata edit, so it happens without re-encoding: only the metadata boxes are rewritten and the result is ready in moments. You can combine it with other edits, such as a new Title or chapters, before you download.
With FFmpeg instead
FFmpeg’s documentation shows how to add an embedded cover on the command line:
ffmpeg -i in.mp4 -i cover.png -map 0 -map 1 -c copy -c:v:1 png -disposition:v:1 attached_pic out.mp4
This adds the image as an extra picture stream marked as attached artwork, and copies the original streams. It suits batches; for one file the browser is quicker to check, because you can see the frame you are choosing.
MP4 thumbnails: questions
Will YouTube use the thumbnail I embed?
No. YouTube suggests frames itself and, for verified accounts, lets you upload a custom thumbnail in YouTube Studio (JPG or PNG, 16:9). The embedded cover art is ignored by YouTube and by most other platforms.
Does adding a thumbnail re-encode the video?
No. Only the metadata boxes are rewritten. The video and audio are copied byte for byte, and the file grows by about the size of the image.
Can I remove a thumbnail from an MP4?
Yes. Press Remove cover art and download the new file. Remove all metadata also removes it, along with every other tag; see remove metadata from video.
Why does Windows still show the old thumbnail?
Windows keeps a thumbnail cache. Check that you are looking at the new copy, change the folder view, or clear thumbnails with Disk Cleanup.
Can I add a thumbnail to an MKV or AVI?
Not here. Cover art is written only to MP4 and MOV files. MKV stores artwork as an attachment, which tools such as MKVToolNix can add.
Does it work with iPhone videos?
Yes. iPhone MOV files take cover art like MP4s, and you can do it in Safari on the phone.