The quick answer: 1280 by 720, under 2 MB, bottom right corner kept clear
You finished the thumbnail, it looked great at full size, and then the video went live and the duration badge sat on your face, your logo or the last word of the headline. Design for a 16:9 picture of at least 1280 by 720 pixels, saved as a JPG or PNG under 2 MB, with nothing important in the bottom right corner. The thumbnail tester checks all of that and shows where the badge lands.
- Build the thumbnail at 1280 by 720 pixels or larger, in 16:9.
- Keep faces, logos and the last word of any text out of the bottom right corner, and away from the top right edge.
- Add the image to the tester, type your title and the video's length, and switch on Badge corner.
- Open the up-next layout, which is only about 168 pixels wide, and check that every word is still readable.
- Export a JPG under 2 MB and upload it.
The image stays in your browser tab. Nothing is uploaded, which you can confirm in the Network tab of your browser's developer tools.
The size, shape and file rules
These are the limits the tester checks today, taken from YouTube's help pages. YouTube can change them, so if the upload screen in YouTube Studio ever disagrees, believe the upload screen.
| Setting | What to use | Otherwise |
|---|---|---|
| Pixels | 1280 by 720 or larger. YouTube now recommends up to 3840 by 2160 | Under 640 wide is too small to use. Under 1280 by 720 can look soft on TVs |
| Shape | 16:9 | Black bars at the sides or above and below |
| File size | Under 2 MB for the mobile app. A computer allows up to 50 MB | The app refuses more than 2 MB |
| Format | JPG or PNG | WebP and AVIF are flagged, so convert them first |
A 3840 by 2160 image has nine times the pixels of a 1280 by 720 one (8,294,400 against 921,600). Unless you need the sharpness for TVs, design at 1280 by 720. A JPG export usually lands well under 2 MB, while a PNG of a busy photo can pass it.
Which corners get covered
Almost every feed stamps the video's duration in the bottom right corner of the thumbnail, which is exactly where designers like to put a face or the end of a headline. The tester outlines the area it covers on your image, and a second outline in the top right marks where some feeds show small buttons on hover.
| Corner | What lands there | What to do |
|---|---|---|
| Bottom right | The duration badge (the timestamp) | Keep faces, logos and final words out |
| Top right | Small buttons that some feeds show on hover | Keep essentials away from this edge |
As the tester draws it, the badge zone is about 26 percent of the width and 24 percent of the height, measured from the bottom right. On a 1280 by 720 image that is roughly 333 by 173 pixels. Treat it as a generous guide and not as a measurement of YouTube: the real badge is narrower on a 45 second video than on one that runs past an hour, and feeds change their layouts often. An easy layout puts the subject on one side and the words on the other, both clear of that corner.
Desktop, phone and up next: how small it really gets
You design at 1280 pixels wide and viewers see a fraction of that. The last column is plain arithmetic: how tall a letter that is 100 pixels tall on the 1280 pixel original ends up.
| Layout in the tester | Width | Scale | A 100 pixel letter becomes |
|---|---|---|---|
| Home feed on a laptop | About 360 px | 28% | 28 px |
| Phone feed | Up to 390 px | 30% | 30 px |
| Up next | 168 px | 13% | 13 px |
A 100 pixel letter is 14 percent of a 720 pixel tall picture. As a rule of thumb, make the letters of your main word at least that tall relative to the picture, and they should stay readable in the up-next list. On a 3840 by 2160 canvas, the same 14 percent is a letter about 300 pixels tall.
Use fewer, bigger words, give the picture one focal point, and flip the tester to dark mode, where thin dark outlines melt into a black page.
Preview it next to the competition
A thumbnail is judged in a crowd. The tester can surround your image with colorful placeholders, as a crowded feed would, and Shuffle moves your position so you can see whether it still catches the eye in a corner. Add two to six versions and open Compare to see each as a home feed card, an up-next card and a phone card, labeled A, B and C. The smallest size is usually the deciding test.
To put a real rival beside yours, use the thumbnail grabber to send its thumbnail to the tester, then press Add version and add your own.
Get to the right size, then under the limit
| You have | Use | Why |
|---|---|---|
| A frame or photo that is not 16:9 | Social image resizer | YouTube sizes built in. Drag and zoom to choose what stays, or fit the whole picture on a blurred background. Shows the real file size |
| A folder of thumbnails to fix | Resize image | Exact pixels in bulk. A smaller picture is not enlarged unless you allow it, and enlarging only makes it soft |
| A file over 2 MB | Image compressor | Switch on Stay under a file size and enter 2,000 KB |
The 2,000 KB entry is a safe margin. The compressor counts a kilobyte as 1,000 bytes, so the file should end up under 2,000,000 bytes, below the 2,097,152 bytes (2 times 1,024 times 1,024) the tester uses for its check. JPG suits a photographic background. PNG keeps text edges crisp but is larger, and JPG vs PNG vs WebP vs AVIF explains the choice. To get a 16:9 crop from a photo, see crop a photo to a ratio or an exact size.
Downloading another video's thumbnail
The thumbnail grabber takes a watch, youtu.be, Shorts, live, embed or mobile link, or a bare 11 character video ID, and lists the sizes YouTube keeps for that video: 1280 by 720, 640 by 480, 480 by 360, 320 by 180 and 120 by 90, plus the vertical cover many Shorts have, when you paste a Shorts link. Your browser fetches them straight from YouTube, so nothing passes through ClipLime.
- The HD size can be missing. When a size does not exist, YouTube returns a tiny gray placeholder, and the grabber measures every image so it can mark missing sizes.
- Three sizes can have black bars. The 640 by 480, 480 by 360 and 120 by 90 images are 4:3, so widescreen videos get bars above and below. When the grabber finds bars, Remove black bars gives a clean 16:9 crop.
- At the time of writing, public copies stop at 1280 by 720, even for a 4K upload. Your design file is the only source of a full resolution original.
- A copied link follows the creator. If the thumbnail changes or the video goes, so does the link. Download the file to keep it.
A thumbnail is someone's work. Keep a saved one for reference and comparison, and ask the creator before you reuse it.
What goes wrong, and the fix
- The face is half behind the timestamp. Move the subject toward the left or the middle and re-check with Badge corner.
- Black bars in the feed. The image is not 16:9. Crop it in the social image resizer.
- The phone app refuses the file. It is over 2 MB. Export a JPG or compress it to 2,000 KB.
- The text is a smudge in the up-next list. Cut words and make the rest bigger.
Shorts, stills and what to do next
The tester is built for 16:9 video thumbnails. For vertical Shorts, the safe zone checker shows what buttons and captions will cover, and the vertical video guide covers sizes and crops. For a sharp starting image, pull a still from your footage with the frame grabber, then size it and test it as above.