YouTube Thumbnail Preview & Checker
Add the thumbnail you made and instantly see how it looks in the home feed, search results, on a phone and in the Up next list. The tool checks size, aspect ratio and file size, warns when text sits under the duration badge, shows whether it stays readable at small sizes, and can fix it to 1280×720 under 2 MB.
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How to use
- Drop your thumbnail image or click to choose it. It opens only in this browser.
- Review the check results: ratio, width, file size, format, and anything marked "Check".
- Under "Covered areas", make sure the duration badge and progress bar don't cover text or faces.
- In the feed preview, switch between home, search, phone and Up next, and between light and dark mode. You can type your own title too.
- Have two versions? Drop the second one into "Thumbnail B" to compare them side by side.
- If needed, choose a size and file-size target under "Fix & save" and save a JPG.
Source: YouTube Help "Add video thumbnails" (checked October 5, 2026): JPG or PNG, minimum width 640px, 16:9 recommended for videos, 2 MB when uploading from mobile and 50 MB from desktop. The covered-area and contrast warnings are estimates from image analysis, for reference only. The preview is a mock-up modeled on a typical video feed, and this site is not affiliated with YouTube.
A quick checklist for a better thumbnail
You design thumbnails on a big screen, but most people see them on a phone, about the size of a fingernail. So the most important test is to look at the thumbnail at the size people actually see it. The small-size preview draws it at search-result size (360×202), small-screen home feed size (246×138) and Up next size (168×94). If your key words are readable at the smallest size, it will work almost everywhere.
The bottom-right corner is always covered by the duration badge. Keep titles, faces and products away from it and inside a 5% safe margin. Watched videos also get a progress bar along the bottom edge, so avoid placing text right at the bottom.
Lots of people use dark mode. A thumbnail with a near-black background can lose its edges in a dark feed and stand out less. Switch to "Dark mode" and, if it fades away, add a lighter border or increase the background contrast. When you can't decide between two versions, put the second in slot B and see which one catches your eye first in the same feed.
FAQ
Is my thumbnail uploaded to a server?
No. The image you choose is opened and checked only in this browser. The fixed image is also created in your browser and saved straight to your device, without being sent anywhere.
What size and file size should a YouTube thumbnail be?
According to the YouTube Help article "Add video thumbnails" (checked October 5, 2026), use JPG or PNG, a minimum width of 640px and a 16:9 ratio for videos. The file can be up to 2 MB when uploading from mobile and 50 MB from desktop. The most common size is 1280×720.
What does the warning about text in the bottom-right corner mean?
The video duration (e.g. 12:34) is shown on top of the bottom-right corner of thumbnails in the feed. If text or a face sits there, it may be covered, so the tool estimates whether that area has fine detail. Turn on "Show covered areas" and double-check with your own eyes.
What if my image is not 16:9 or is larger than 2 MB?
In "Fix & save", choose a size (such as 1280×720) and how to fit it (crop to 16:9, or show all on a blurred background), and set the file-size target to under 2 MB. The tool adjusts the JPG quality automatically.
Can I load or download thumbnails from other people's videos?
No. This tool only opens image files you already have. Other creators' thumbnails may be copyrighted, so there is no feature to fetch or download them. To make a new thumbnail, try the YouTube Thumbnail Maker.
Is the preview exactly the same as YouTube?
It is a mock-up of a typical video feed, so layout and sizes can differ by device, screen size and platform updates. The other thumbnails and titles around yours are examples drawn by this tool. This site is not affiliated with YouTube.