YouTube Thumbnail Tester
See your thumbnail the way viewers will: in the home feed, on a phone, in the suggested column at 168 pixels. Compare up to three, squint at them, and find out what YouTube's duration badge is about to cover. Nothing is uploaded.
Where a YouTube thumbnail is actually seen
A thumbnail is made once, at 1280 × 720 or larger, and shown at a handful of much smaller sizes. The sizes below are what the previews on this page imitate. They are approximate: YouTube's layout changes with the window and the device, and the numbers move a little from one redesign to the next.
| Surface | Approximate width | What breaks first |
|---|---|---|
| Home feed, desktop | 320 to 360 px | Fine text, small faces |
| Home feed, phone | Full screen width, 360 to 430 px | Low contrast against the white or dark app background |
| Suggested videos, desktop sidebar | 168 px | Anything that is not the single main subject |
| Search results, desktop | 360 px | Text longer than three or four words |
| Duration badge | Bottom-right corner, over the image | Whatever you placed there |
YouTube's own requirements for the file (3840 × 2160 recommended, 640 pixels minimum width, 2 MB from the phone app) are on its custom-thumbnails help page. If yours fails the shape or size check above, the free thumbnail resizer fixes both without leaving the browser.
Questions about testing YouTube thumbnails
How do I test a YouTube thumbnail before uploading it?
Look at it the way a viewer will, not the way you made it. A thumbnail is designed at 1280 × 720 or larger and seen at 320 pixels wide on a desktop home page, around 360 on a phone, and 168 in the suggested-videos column. Drop the image above and this page shows all three, with a real title underneath, next to a blur toggle that imitates a viewer scrolling past. If the subject, the emotion and any text still read at 168 pixels, it will do its job. If they do not, you now know what to simplify before anyone sees it.
What does the duration-badge check mean?
YouTube prints the video's length in the bottom-right corner of every thumbnail, over your image, in a dark rounded box. Anything you put there is covered: a face, a number, the last word of your text. This page measures the bottom-right 15% of the image and flags it when that corner carries as much detail as the rest of the picture. Keep that corner quiet. The same rule is enforced on every image our generator produces.
Can I compare two thumbnails to see which is better?
You can put up to three side by side at suggested-video size, which is the fairest comparison: it is the smallest surface a thumbnail has to win on, and the one where differences in contrast and simplicity show most. What this page cannot do is tell you which one real viewers will click. For that, YouTube's own Test & Compare feature in YouTube Studio shows up to three thumbnails to different viewers and keeps the one that earns the most watch time. Use this page to pick the three worth testing, then let YouTube run the test.
Is my thumbnail uploaded anywhere?
No. The previews and the measurements run in your browser, on your own device, using the canvas element your browser already has. An image you drop here is never sent to our servers. If you paste a YouTube link instead, our server fetches that video's public thumbnail from YouTube and passes it to your browser, which is where the analysis happens.
What is a good click-through rate for a thumbnail?
YouTube says half of all channels sit between 2% and 10%, and the number depends heavily on where the impressions come from: suggested videos and browse features behave differently from search. A new thumbnail is worth judging against the same video's previous rate, not against another channel. The comparison tools here help you choose a version that will at least be seen clearly; the rate itself you read in YouTube Studio a week after publishing.
Testing a competitor's thumbnail? The thumbnail downloader pulls any video's image at full size. Need to change the words on yours first? The free text editor does that in the browser too. And what counts as a good click-through rate explains the number you will be reading in Studio afterwards.