YouTube now recommends uploading video thumbnails at 3840 by 2160 pixels, in a 16:9 ratio, with a minimum width of 640 pixels. Use JPG or PNG. Files can be up to 50 MB when you upload from a computer and 2 MB from a phone. 1280 by 720 still works and stays the practical minimum for a sharp image.
The pixel numbers are the easy part. The harder part is that your carefully made image will mostly be seen at a fraction of that size, on a phone, next to other thumbnails. This guide covers the specs, the safe zones and how to design for the size your thumbnail is actually seen at. For the ideas behind a good thumbnail, see our guide to thumbnail concepts.
The specs at a glance
| Spec | Value |
|---|---|
| Recommended size | 3840 x 2160 pixels |
| Aspect ratio | 16:9 |
| Minimum width | 640 pixels (1280 x 720 is the practical minimum) |
| Formats | JPG or PNG |
| File size | Up to 50 MB from a computer, 2 MB from a phone |
If your image is not 16:9, YouTube will add black bars or crop it, depending on where it appears. Always export at exactly 16:9.
Why 3840 by 2160
For years the standard was 1280 by 720 with a 2 MB limit. In late 2025 YouTube raised the limit to 50 MB so it could serve 4K thumbnails, mainly for TVs, where thumbnails are shown far larger than on a phone. Designing at 3840 by 2160 keeps every surface sharp. If your editor or workflow is built around 1280 by 720, that size is still accepted; scale up proportionally when you can, and keep the 16:9 ratio.
The size that really matters
On a phone, a thumbnail in the Home feed is a few centimeters wide. In Suggested, next to a video, it is smaller still. That changes how you should design:
- Text needs to be much larger than feels natural on a monitor. Three or four words at most.
- The subject should fill a large part of the frame. A face that looks fine at full size can become a dot.
- Fine detail disappears. Thin lines, small objects and subtle textures do not survive.
The practical rule: always preview your thumbnail at about the width of your thumb before publishing. Our guide on thumbnail text that works on mobile goes into detail.
Safe zones
Some parts of a thumbnail are covered or cropped in certain places:
- Bottom right corner. YouTube places the video duration here. Keep important elements away from it.
- Bottom edge. Progress bars for partly watched videos appear along the bottom.
- Edges in general. Some layouts round the corners or crop slightly. Keep text and faces away from the very edge.
For Shorts, the rules are different, because vertical videos are displayed in several shapes. See YouTube Shorts thumbnail size.
Choosing the right format
- JPG is the usual choice for photo-based thumbnails. It keeps files small, but heavy compression blurs text and edges.
- PNG keeps sharp edges and text crisp, at the cost of larger files.
- Uploading from a phone? The limit there is 2 MB, so a large PNG may be rejected. Export a JPG, or upload from a computer.
If text looks soft after upload, export as PNG or use a higher JPG quality setting.
Color and file settings
Export in the sRGB color profile. Images in other profiles can look dull or oversaturated once YouTube processes them. If your editor offers a “for web” export, it usually handles this for you.
Size and the other surfaces
Your thumbnail appears in many sizes: large on TV, medium on desktop Home, small in mobile feeds and smaller still in Suggested. A design that works at the smallest size will work everywhere. The reverse is rarely true. The free KiThumbs Thumbnail Roaster shows your thumbnail in realistic layouts so you can check them all at once.
Frequently asked questions
What happens if my thumbnail is smaller than recommended?
YouTube accepts images with a minimum width of 640 pixels, but small images can look blurry, especially on larger screens and TVs. In its A/B tests, if any thumbnail is below 1280 by 720, YouTube downscales all the versions in the test to 854 by 480. Export at 1280 by 720 at the very least, and at 3840 by 2160 when you can.
Can I upload a 4K thumbnail?
Yes. YouTube recommends 3840 by 2160 for video thumbnails and accepts files up to 50 MB when you upload from a computer. From a phone the limit is 2 MB.
What size should text be on a YouTube thumbnail?
There is no official number. What matters is that it reads instantly at phone size. If you have to concentrate to read it when the thumbnail is small, make it larger or use fewer words.
Is the thumbnail size the same for Shorts?
No. YouTube recommends 2160 by 3840 pixels in a 9:16 ratio for Shorts, and their thumbnails are shown in different shapes depending on the surface. Our Shorts thumbnail size guide explains what to do.
Sources
- YouTube Help: Add custom thumbnails on YouTube
- 9to5Google: YouTube raising thumbnail file size limits for 4K
Your test this week
Open your last five thumbnails on your phone in the YouTube app and look at each for one second in the Home feed or your channel page. Write down which ones you could read instantly and which ones you could not. Compare that list with each video’s CTR against your channel median.