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📐 Thumbnail Dimensions Checker

Upload your thumbnail (it never leaves your device) or type the dimensions, and get a pass/fix report against every rule YouTube enforces for custom thumbnails.

Upload your thumbnail image (checked locally, never uploaded)

Or enter width (px)

Height (px)

About this tool

YouTube rejects or quietly degrades thumbnails that break its technical rules: the recommended size is exactly 1280×720 pixels, the aspect ratio must be 16:9, the width must be at least 640 pixels, and the file must be under 2 MB in JPG, PNG, GIF or BMP format. A design that is even slightly off-ratio gets letter-boxed or centre-cropped by YouTube's player crops — which can cut off your text.

This checker reads the real pixel dimensions of the file you drop in (the image is processed in your browser and never sent anywhere) and reports each rule separately, so you know whether you need a resize, a re-crop or just a smaller export — instead of a single vague 'looks fine'.

How to use it

Upload the exact file you plan to give YouTube — not a screenshot of it.
Read the report line by line: resolution, ratio, minimum width and (for uploads) file size.
Fix any FIX line in your editor: resize to 1280×720 and export under 2 MB.
Re-check the exported file once before uploading; exports often differ from the working canvas.

Tips from real creator workflows

Design inside a safe zone: keep faces and text at least 60px from every edge — TV and search crops eat the borders.
A PNG screenshot-style thumbnail can silently pass 2 MB; exporting as high-quality JPG usually halves the size with no visible difference.
Check the file from your phone too if you designed on desktop — editors sometimes export at 2× scale (2560×1440).

Frequently asked questions

Does my image get uploaded to your server?

No. The file is read by your own browser using built-in image handling; nothing is transmitted. You can verify by using the tool with your internet disconnected after the page loads.

My thumbnail is 1920×1080 — is that a problem?

The ratio is right (16:9), so YouTube will accept and downscale it. It still works, but 1280×720 is the size YouTube itself recommends and serves, and the smaller file uploads faster with identical on-screen quality.

What formats does YouTube accept?

JPG, PNG, GIF and BMP. In practice JPG or PNG covers every case; avoid animated GIFs, which YouTube does not animate on thumbnails.

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