Utility
Thumbnail Previewer
The Thumbnail Previewer shows how a thumbnail actually appears where viewers see it. Small, alongside other videos, at desktop and mobile sizes. Most thumbnails are designed full-size and fail at the size they are really viewed at.
How it works
How to use the Thumbnail Previewer
Three steps, no account and nothing to install.
Why previewing at real size matters
A thumbnail is uploaded at 1280×720 but is usually seen at around 360×200 on desktop search and smaller still in mobile feeds. Detail that looks sharp in your design tool disappears entirely. If your thumbnail's message is not readable as a small rectangle. It is not doing its job.
What survives at small sizes
Large faces with clear expressions, high contrast between subject and background, and no more than three or four words of text. What fails: small text, busy backgrounds, thin fonts, and anything relying on fine detail. A useful test is to shrink your thumbnail to thumbnail size and view it from across the room. If you cannot tell what the video is about, simplify.
FAQ
Frequently asked questions
1280×720 pixels, 16:9 aspect ratio, under 2MB, in JPG, PNG, GIF or BMP format.
Three to four words at most. The title next to the thumbnail carries the detail, the thumbnail's job is to be readable in a fraction of a second.
This tool previews thumbnails of published videos. For unpublished designs, set the video to unlisted, upload the thumbnail, and preview it here before going public.
Mobile renders it far smaller and crops differently in some surfaces. Always check the mobile preview, since most YouTube viewing is on phones.
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