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About this tool
Crop and export any image to YouTube's 1280x720 16:9 thumbnail spec, with minimum-width, aspect-ratio and 2 MB file-size checks.
YouTube Thumbnail Size Generator resizes any image to YouTube's thumbnail specification — 1280 x 720 pixels, 16:9, at least 640 pixels wide and under the 2 MB upload limit — and reports whether the result passes each of those rules. It centre-crops or letterboxes the source, shows how much of the original is lost at 16:9, measures the encoded JPEG, PNG or WebP size before you upload, and marks the bottom-right corner where the duration badge sits. All processing happens in the browser, so the image is never uploaded anywhere.
Open YouTube Thumbnail Size Generator on AltFTool — it loads instantly in your browser.
Provide your input — an image, text, or data.
Let the tool analyze or generate the result.
Review, refine, and reuse the output wherever you need it.
Minimum width, 16:9 ratio, recommended resolution and the 2 MB limit are each checked and labelled pass, warn or fail.
File size comes from encoding the actual canvas at your chosen quality, not from an estimate.
The image is decoded and re-encoded locally; nothing is sent to a server.
1280 x 720 pixels at a 16:9 aspect ratio. YouTube requires a minimum width of 640 pixels and rejects thumbnail files larger than 2 MB, and accepts JPG, GIF, PNG and WebP.
The 2 MB cap applies to the file, not the pixel dimensions, so a 1920 x 1080 PNG often fails while the same image as an 85% quality JPEG passes comfortably. Export as JPEG or WebP and drop the quality slider until the measured size sits under 2 MB.
Only if it is not 16:9. YouTube fits non-16:9 thumbnails into a 16:9 frame, which produces black bars or a crop depending on where it appears. Exporting at 1280 x 720 avoids the problem entirely, and this tool shows the exact percentage of the original that a centre crop removes.
Marginally, on large screens. 1920 x 1080 gives YouTube more detail to downscale from, but the thumbnail is most often seen at around 246 pixels wide in search and sidebar listings, so legibility of the largest text matters far more than resolution.