YouTube's own specification: 3840 x 2160 for videos and 2160 x 3840 for Shorts, a 640-pixel minimum, JPG or PNG, the file-size limits, and the verified-account rule.
Add custom thumbnails on YouTube
YouTube Nov 2026
Open support.google.com →Make the thumbnail in Canva or Photopea, use AI only for the parts you cannot draw, and let YouTube's own test pick the winner. Canva has a free plan, and Pro from $12 a month billed yearly; Photopea does the same free in the browser with Photoshop-style layers and masks. For a background, a product shot or large lettering, ask ChatGPT or Gemini, both free with limits, or Ideogram, built for text inside images, whose free plan can use all its models. Then upload up to 3 versions to YouTube Studio's A/B test on a computer, and YouTube shows everyone the title and thumbnail with the most watch time. YouTube recommends 3840 x 2160 pixels for a video thumbnail and 2160 x 3840 for a Short, at least 640 pixels wide, in JPG or PNG, and custom thumbnails need a verified account. Rule: design it in Canva, test three, keep the one viewers chose.
Part of YouTube on eChai Explore.
On the AI map, 29 October 2026 Video generation Images Avatars and voice Music and audio Video editing
7 resources.
YouTube's own specification: 3840 x 2160 for videos and 2160 x 3840 for Shorts, a 640-pixel minimum, JPG or PNG, the file-size limits, and the verified-account rule.
YouTube Nov 2026
Open support.google.com →How to test up to 3 titles or thumbnails in YouTube Studio; the one with the highest watch time is shown to everyone, and who is eligible.
YouTube Nov 2026
Open support.google.com →A free browser editor with layers, masks and blending that opens and saves PSD files, enough to build a thumbnail from scratch.
Photopea Nov 2026
Open photopea.com →Ideogram's image models, built to get the words in an image right; every plan, free included, can use all of them.
Ideogram Nov 2026
Open docs.ideogram.ai →How to make a background or edit your own photo by describing it, free in the Gemini app.
Google Nov 2026
Open support.google.com →Includes a tested review of Canva as an all-in-one design platform, with its free plan and Pro at $12 a month billed yearly.
Zapier (Miguel Rebelo) Oct 2026
Open zapier.com →Hands-on comparison of ChatGPT, Nano Banana, Midjourney and others, including how well each now renders text for posters and thumbnails.
Zapier (Harry Guinness) Oct 2026
Open zapier.com →The same ground, over in Brand, web & content, our Starting Up track.