Free tool
Thumbnail tester see it in the feed before you upload.
Drop a YouTube thumbnail and see it at real size in the home feed, search results, the sidebar and on a phone, light or dark, next to other videos. Compare two versions.
Previewed with placeholder videos, not the live feed.
Thumbnail tester at a glance
content.win previews thumbnails at the real YouTube sizes, free.
- Works with
- JPG, PNG and WebP.
- Comes back as
- Your thumbnail shown at every size YouTube uses, on desktop and phone, next to real competition.
- Runs
- In your browser.
- Limits
- No daily limit and no cap on how many files.
- Price
- Free. No account, no watermark.
How to test a thumbnail before uploading
- Drop the thumbnail in. One image, or two to compare A against B in the same feed. Add the title you plan to use and your channel name so the card reads like the real thing.
- Look at it where people see it. Home shows the desktop grid, Search the results list, Sidebar the small suggested-video size, Phone the mobile feed. Switch to dark, which most viewers use.
- Fix what disappears. If the text is unreadable in the sidebar or the face is a smudge on the phone, change the thumbnail, not the title. Download the mockup to share with a client or editor.
What to check at small size
- Three words at most
- Text on a thumbnail is read at about 168 pixels wide in the sidebar. Anything longer than three big words becomes texture. The title already carries the sentence.
- One face, one object
- A clear face with a readable expression and one object the video is about. Crowded frames lose the eye at feed size.
- Contrast against both feeds
- YouTube is white by day and near-black in dark mode. A thumbnail with a dark edge vanishes into the dark feed; a white one vanishes into the light feed. Check both.
- The bottom-right corner
- The length badge sits there. Keep text and faces out of it.
- Next to the competition
- The feed is full of other bright thumbnails. Yours needs one strong color and one focal point, not more of everything.
YouTube thumbnail specs
- Size
- 1280 × 720 pixels, a 16:9 ratio, at least 640 pixels wide. Upload the full 1280 × 720; YouTube scales it down everywhere it appears.
- File
- Under 2 MB. JPG, PNG, GIF (still) or BMP. WebP works in the studio too. A JPG at quality 85 to 90 usually lands around 200 KB.
- A/B testing on YouTube
- YouTube Studio can test up to three thumbnails on the same video for channels that have the feature. This page is the eye test before that: does it read at feed size at all.
Good to know
- The other videos in the preview are neutral placeholders, not real channels.
Questions people ask
How do I preview a YouTube thumbnail before uploading?
Drop the image here and it appears inside a mock home feed, search results, the sidebar and a phone feed, with your title and channel name. That shows the thumbnail at the sizes viewers actually see, which is the check that matters.
What size should a YouTube thumbnail be?
1280 × 720 pixels, 16:9, under 2 MB, as JPG, PNG, GIF or BMP. The checks row on this page flags a wrong ratio, a small image or a file over the limit.
Why does my thumbnail look blurry on YouTube?
Usually the source is smaller than 1280 × 720 and gets scaled up, or the text is thin and disappears when the image is shrunk to 168 pixels for the sidebar. Upload the full size and use thick, short text.
Can I compare two thumbnails?
Yes. Drop two images, or add a version B after the first. Both sit in the same feed among the same placeholders so you can judge which one pulls the eye.
Does it show the real YouTube feed?
No. The other videos are neutral placeholders drawn to YouTube's layout and sizes. That keeps the comparison fair and avoids loading anyone else's content into your test.
Is the thumbnail tester free?
Yes, with no account, no watermark and no upload.