A thumbnail has a big say in whether a video gets watched. But following the specification is not enough on its own, because thumbnails are displayed far smaller than they look while you are making them. Here are the specs, and separately, how to keep a thumbnail readable when it is small.
The specification
YouTube Help lists these conditions for regular videos (checked in September 2026):
- A resolution of 3,840 × 2,160 pixels, with a minimum width of 640 pixels
- A 16:9 aspect ratio
- Formats such as JPG and PNG
- A file size limit of 50 MB from a computer, or 2 MB from mobile
Note that the ratio is different for Shorts (9:16) and for podcast playlists (1:1).
The same thumbnail at the sizes it is shown
Below is the same thumbnail at three sizes. While you are making it, you see it at something like the size on the left, but in a phone feed or the related videos column it shrinks to about the size of the two on the right.
Sunset shots12:34Sunset shots12:34Sunset shots12:34This gap is hard to notice while you work, so make a habit of shrinking the finished image to check it. Scaling it to around 10% and seeing whether the content can still be made out is enough.
How much text fits
Given that it will be shown small, very little text fits. Below are a thumbnail with a lot of text and one with little, at the same small size.
Sunset photography for beginners: the basic settings and compositionJust 3 tweaksAs a rough guide, keep it to a few short words, and no more than two lines, so the text stays legible. The video title appears next to the thumbnail, so there is no need to repeat it. A thumbnail works better carrying a phrase the title cannot convey.
Keep the contrast high
If text and background are close in brightness, the text becomes unreadable when scaled down. A dark band behind the text, as in the samples above, keeps it readable whatever the picture behind it. Thin typefaces suffer at small sizes, so a heavier weight is the safer choice.
Leave the bottom right alone
The video duration is overlaid on the bottom-right corner of the thumbnail, where “12:34” sits in the samples above. Anything you place there will be covered, so keep it clear.
What you cannot use
Photographs taken by others, characters, company logos and images of public figures cannot be used without permission. Sensationalised images unrelated to the video are treated as a guideline violation. If you use stock assets, always confirm that commercial use is permitted.
About Visual Hub assets
Our landscape assets are 1408 × 768 pixels, close to 16:9. That meets the 640-pixel minimum width but falls short of the recommended resolution. They are intended as a background that you enlarge to the size you need before adding text. The files we distribute are WebP, so pick “PNG” or “JPG” on the asset page and save it in that format.
Sources
- YouTube Help: Add custom thumbnails on YouTube
Information as of September 2026, when this article was written.