YouTube Thumbnail Preview Tool

See how your thumbnail and title will look on YouTube before you publish. Test it on the home feed, search, sidebar and mobile, in light or dark mode, next to real videos.

Thumbnail
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    How to use the thumbnail preview tool

    1. Upload your thumbnail and type your title. Everything stays in your browser. Nothing is uploaded to a server.
    2. Add real competitor videos by pasting their links, so you can see your thumbnail next to the ones it will compete with.
    3. Switch layouts and themes. Check it's readable in the small sidebar size, on a phone and in dark mode, then shuffle its position.

    What makes a thumbnail stand out

    • Readable when tiny. In the sidebar and on mobile, thumbnails are shown around 168 pixels wide. If you can't read the text in the Sidebar view, use fewer, bigger words.
    • One clear subject. A face, object or result that's recognisable at a glance beats a busy collage.
    • Contrast with the feed. Compare against the real videos you loaded. If yours blends in with their colours, try the opposite.
    • Mind the corner. The duration badge covers the bottom-right corner, so keep important details out of it.
    • Title and thumbnail work together. Don't repeat the title in the image. Let each add something.
    • Check the cut-off. Long titles get truncated after two lines. Front-load the most important words.

    Need the exact dimensions? See the YouTube thumbnail size guide.

    Frequently asked questions

    How can I preview my YouTube thumbnail before uploading?

    Upload your image to ThumbDL's thumbnail preview tool and type your title. You'll see a realistic mock-up of the YouTube home feed, search results, sidebar and mobile app, in both light and dark mode.

    Is my thumbnail uploaded anywhere?

    No. Your image is processed entirely in your browser and never leaves your device.

    What size should my thumbnail be?

    Use 1280×720 pixels (16:9) as a JPG, PNG or GIF under 2 MB. The tool checks your image against these requirements automatically.

    How long can a YouTube title be?

    Up to 100 characters, but titles are usually cut off after roughly 60–70 characters depending on the layout. Use the preview to see exactly where yours gets truncated.

    Can I test multiple thumbnails?

    Upload a new image at any time to swap it in and compare. YouTube Studio also has a built-in "Test & Compare" feature that A/B tests up to three thumbnails on real viewers after you publish.

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