YouTube Thumbnail Checker
Upload your thumbnail to check its size, shape and file size, and see how it looks at small sizes. The image stays in your browser and is never uploaded.
What this tool checks
YouTube recommends custom thumbnails of 1280×720 pixels in a 16:9 shape, with a minimum width of 640 pixels, saved as JPG, PNG or GIF. The checker compares your image with these guidelines and shows each result with a short tip if something is off. File size limits have changed over time, so confirm the current limit on YouTube’s upload screen.
Why the small previews matter
Most viewers see your thumbnail small, on a phone or in a list of suggested videos. The previews above show it at three real sizes, with a label where YouTube places the video length. If you can’t read the text or recognize the subject at the smallest size, simplify the design.