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YouTube thumbnail checker & preview

Check your thumbnail's size, contrast and readability, then see it in a mock YouTube feed: home, search, up next and mobile, light and dark.

Feed preview

How it sits in the home feed, search, up next and on mobile, in light and dark.

A mock for judging packaging, not YouTube itself. Grey cards stand in for other videos, and your image never leaves this tab.

How it works

The image is decoded in your browser. Vid0 checks the size against YouTube's specs (16:9, 3840×2160 recommended, 640 pixels wide at least), then measures brightness, contrast, colour, clutter and how well it reads at 168×94, the size of an “up next” card.

The feed preview places it among grey stand-in cards at the sizes YouTube uses, so you can see whether it still reads on a phone and in dark mode. Nothing is uploaded.

Questions

What size should a YouTube thumbnail be?
16:9. YouTube recommends 3840×2160; 1280×720 still looks sharp on most screens, and the minimum width is 640 pixels. Thumbnails uploaded from a computer can be up to 50 MB.
Is my image uploaded anywhere?
No. The checks and the feed preview run in your browser, and the image never leaves this tab.
What does the instant score measure?
Brightness, contrast, colour, clutter and how well it reads at small sizes, blended into a 0 to 100 score. It's a quick heuristic, not a prediction of clicks.
How do I compare two thumbnails?
Check each one here. Signed in, Vid0's thumbnail lab compares up to three variants side by side among real competing videos, with an AI critique. See pricing.
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Vid0's thumbnail lab puts up to three variants among real videos from your niche, with an AI critique of each.

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