YouTube thumbnail: size, format and requirements

A YouTube thumbnail is an image of 3840 × 2160 pixels in a 16:9 ratio, in JPG or PNG, weighing up to 50 MB from a computer and up to 2 MB from a phone. Below: what a thumbnail is, how to get a file of exactly that size, what to do with Shorts, and why YouTube may reject your upload.

What is a YouTube thumbnail?

The thumbnail is the image viewers see in place of your video in search, on the home page and in recommendations. YouTube suggests three frames from the video itself, but you can replace them with your own image — that is a custom thumbnail. A good one is not a frame from the middle of the video but a picture of its own: one face or object up close, two or three words in large letters, and contrast that reads even on a phone screen.

What size should a YouTube thumbnail be?

YouTube recommends 3840 × 2160 pixels for regular videos and 2160 × 3840 for Shorts. The minimum width is 640 pixels, so a smaller file with the same ratio is accepted too, but 3840 × 2160 is the size that stays sharp on a TV or a large monitor.

Requirements as stated in YouTube's help on 24 September 2026.

Why a 1920 × 1080 canvas, not 3840 × 2160

The cover here exports at double pixel density: a 1920 × 1080 canvas gives a file of exactly 3840 × 2160 — the size YouTube recommends. So tell the designer “1920 × 1080”, or just “YouTube thumbnail”. A 1280 × 720 canvas works too: the file comes out at 2560 × 1440, still 16:9 and far above the minimum.

From a computer, file size is not an issue: even fully uncompressed, a 3840 × 2160 image is about 33 MB, so a PNG of that size always fits under the 50 MB limit.

How to make a YouTube thumbnail with AI

AI's weak spot is lettering: text drawn straight into a generated image often comes out misspelled. So the work is split in two. The AI paints the background and the main subject, and the caption is set as real text on top — no typos, and editable one word at a time.

1. The video's topic in one phrase — “budget phone review”, “borscht in 30 minutes”.
2. The caption — two to four words, not the whole title: YouTube already shows the title next to the thumbnail.
3. The main subject — a face with a clear emotion, a product, a dish. If it's you, upload your own photo.
4. The platform — write “YouTube” and the canvas will be 1920 × 1080.

Before it is shown, the thumbnail is rendered in a browser and checked: is the caption cropped, is there enough contrast. Edits from there are plain text: “bigger caption”, “make it yellow”, “change it to PART 2”. The background is not redrawn, so the next episode in a series only needs a new caption. You can build and preview the thumbnail on starter tokens; downloading the finished PNG unlocks after your first purchase.

Check the thumbnail before publishing

• Shrink it to feed-card size on a phone. If the caption doesn't read, use fewer words and bigger letters.
• Keep the bottom-right corner clear — YouTube shows the video's duration there.
• The thumbnail should tell the truth about the video. One that promises what the video lacks earns a click and an exit ten seconds later.

YouTube and other platforms

If the video goes out elsewhere too, sizes differ: Rutube, for example, accepts no more than 1920 × 1080 — see the Rutube cover chapter. A summary table for every platform is in the video cover and thumbnail chapter. For Dzen and Telegram a 1920 × 1080 file is enough — see the Dzen video cover and the Telegram video cover. The video itself can be made with AI as well — for example, a video from a text description.

In Twelver chat a thumbnail is built in layers: the image from AI, the caption as real text, a browser check before you see it. Back to the guide to video with AI.