A thumbnail decides much of whether a video gets watched — but meeting the specification is not enough on its own, because thumbnails are displayed far smaller than the size you upload. Here are the specs, and separately, what makes one readable.
The specification
YouTube Help lists the following (as of July 2026):
- A resolution of 3840 × 2160 pixels, with a minimum width of 640 pixels
- A 16:9 aspect ratio, the one most used in YouTube players and previews
- JPG, GIF or PNG
- Up to 50 MB from desktop, or 2 MB from mobile
The 640-pixel minimum width matters when you pick source artwork: anything narrower will be rejected.
Viewers see something much smaller
You upload something large, but on a viewer’s screen the thumbnail is a few centimetres across — smaller still in a phone feed or a sidebar of related videos.
You are designing on a big screen, so this gap is easy to miss. Shrink the finished image and look at it again. Scaling it to around 10% and checking that it still reads is enough.
How much text fits
Given that size, very little. Roughly four to nine characters, and no more than two lines, keeps text legible.
The video title already appears next to the thumbnail. Repeating the title in the image spends the space saying the same thing twice; the thumbnail is better used for what the title cannot carry.
Keep the contrast high
Text and background that sit close in brightness stop being separable once scaled down. Dark text on light areas, light text on dark ones. Over a busy background, add a band behind the text or blur that part of the image.
Thin typefaces suffer most at small sizes; a heavier weight survives better.
Leave the bottom right alone
The video duration is overlaid on the bottom-right corner. 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 artwork, confirm that commercial use is permitted.
About Visual Hub assets
Our landscape assets are 1408 × 768, close to 16:9. That clears the 640-pixel minimum but falls short of the recommended resolution, so they are intended as a background you scale up before adding text. Commercial use is free and no credit line is required.