YouTube Thumbnail Size: What YouTube Actually Recommends
Quick answer
YouTube's own documentation asks for a thumbnail resolution of 3840 x 2160 pixels at 16:9, with a minimum width of 640 px, in JPG or PNG. The file ceiling is 2 MB on mobile and 50 MB on desktop. The 1280 x 720 figure repeated across most guides still works, because it clears the 640 px minimum, but it is not what YouTube recommends.
Every YouTube thumbnail size
| Use | Dimensions | Ratio |
|---|---|---|
| Resolution YouTube statesUse thisThis is what YouTube's own documentation recommends, not the 1280 x 720 repeated across most guides. | 3840 x 2160 | 16:9 |
| Minimum widthBelow this YouTube rejects the upload. | 640 px | 16:9 |
| Long-standing conventionNot published by YouTubeWidely used and comfortably above the 640 px minimum, but not what YouTube documents. | 1280 x 720 | 16:9 |
Formats
JPG or PNG
Maximum file size, mobile
2 MB
Maximum file size, desktop
50 MB
Aspect ratio
16:9
What the table does not tell you
- Design for the 360 px wide render, not the 1280 px file. If the text is unreadable at a third of the size, it is unreadable where the decision actually gets made.
- The video duration stamp sits in the bottom right corner. Keep faces and text out of roughly the bottom right eighth of the frame.
- Custom thumbnails require a verified channel. Without verification YouTube only offers three auto-generated frames.
- The file ceiling depends on where you upload from: 2 MB on mobile, 50 MB on desktop. A 3840 x 2160 PNG will breach the mobile limit easily, so export as JPG or upload from desktop.
Stop resizing the same asset five times
Crowbert formats one upload for every platform it publishes to, so a single thumbnail goes out at the right dimensions everywhere without a round trip through a design tool.
Common questions
What is the best YouTube thumbnail size?
YouTube documents 3840 x 2160 at 16:9. Most guides say 1280 x 720, which still works because it clears the 640 px minimum comfortably, but it is not the figure YouTube publishes. If you are exporting fresh, export at 3840 x 2160.
Why was my YouTube thumbnail rejected?
Usually file size, and usually on a phone. The ceiling is 2 MB on mobile against 50 MB on desktop, so the same file can upload from a laptop and fail from an app. The other common cause is an unverified channel, which disables custom thumbnails entirely.
Can I use a 4K thumbnail on YouTube?
You can upload larger, but there is no benefit. YouTube downscales everything and the 2 MB ceiling makes a high-resolution file harder to fit without heavier compression.
Other YouTube sizes
Master YouTube next
Sizes on other platforms
Where these numbers come from
Figures marked “not published by YouTube” are working conventions rather than documented specifications. Everything else comes from the documentation above.
Checked against the documentation above on September 22, 2026.