YouTube Thumbnail Size Checker
Drop in your thumbnail and see instantly whether its size, aspect ratio, resolution and file size fit YouTube's limits, with a safe-zone overlay showing what could get clipped.
Drop your thumbnail here
or click to browse
Checked in your browser. Your image is never uploaded.
YouTube thumbnail size at a glance
- Aspect ratio
- 16:9 for videos (9:16 for Shorts)
- Resolution
- 3840×2160 per YouTube's Help Center. 1280×720 is the classic standard and still works. Minimum width 640 px.
- Format
- JPG or PNG
- File size
- Up to 2 MB from mobile, up to 50 MB from desktop
Checked against YouTube's custom thumbnail help page in September 2026. Want the full breakdown, including Shorts? Read the YouTube thumbnail size guide.
How to use the thumbnail size checker
- Drop your thumbnail into the box above, or click to choose a file.
- Read the four checks: file format, aspect ratio, resolution, and file size.
- Look at the safe-zone overlay to see which parts of the image could be clipped or covered.
- Fix anything marked with a warning or a failure, export again, and check the new file.
Everything runs in your browser. The image never leaves your computer, so you can check as many files as you like.
What each check means
- File format: JPG and PNG pass. Anything else gets a warning, because those are the formats YouTube lists.
- Aspect ratio: 16:9 passes, with a small tolerance so an export that is a pixel off still counts. A vertical 9:16 image gets a warning for regular videos, because that shape is for Shorts. Other shapes may be cropped or shown with bars.
- Resolution: under 640 px wide fails. Between 640 px and 1280 px wide gets a warning because it will look soft when scaled up. 1280×720 and above passes, and 3840×2160 matches the size YouTube's Help Center lists.
- File size: under 2 MB passes for any device. Between 2 MB and 50 MB gets a warning, because it works from a computer but not from the mobile app. Over 50 MB fails.
The overall verdict at the top combines them: "Ready to upload", "Works, with caveats", or "Fix before uploading".
Common reasons a thumbnail fails, and the fix
- The image is too small. Rebuild it on a 1280×720 canvas or larger instead of stretching a small image.
- The shape is wrong. Set the canvas to 16:9 before you design. Cropping at the end often cuts off text.
- The file is too big. Export a JPG at high quality instead of a PNG. Photo-heavy PNGs can be several megabytes.
- It's in the wrong format. Convert WebP, GIF, or BMP files to JPG or PNG before uploading.
- It looks fine here but blurry on YouTube. The usual causes are low export quality and repeated compression. See why a YouTube thumbnail looks blurry.
Export settings that keep it sharp
- Design on a 16:9 canvas at 1280×720 or larger.
- Export as a JPG at the highest quality that stays under your file limit, or a PNG for flat colors and sharp text.
- Work from an original file. Don't edit a screenshot of a screenshot.
- Upload from a computer if the file is over 2 MB.
Once the file passes, see how it reads small with the thumbnail preview tool, or get a design score from the thumbnail rater.
Frequently asked questions
What size should a YouTube thumbnail be?
Use a 16:9 image. 1280×720 pixels is the long-standing standard and still works. YouTube's Help Center now lists 3840×2160 (4K), with a minimum width of 640 pixels.
What is the maximum YouTube thumbnail file size?
50 MB when uploading from a desktop and 2 MB for video thumbnails when uploading from the mobile app, according to YouTube's Help Center. The limit used to be 2 MB everywhere.
What is the YouTube thumbnail safe zone?
The part of the frame that is least likely to be clipped or covered. Keep faces and text inside the center 80% of the image, and away from the bottom-right corner, where YouTube overlays the video's duration.
Is 1920x1080 a good YouTube thumbnail size?
Yes. It's 16:9 and well above the 640 px minimum width, so the checker passes it. It's sharper than 1280x720 and usually still small enough to stay under 2 MB as a JPG.
Why does the checker warn me about file size?
A warning means the file is over the 2 MB limit YouTube lists for mobile uploads but under the 50 MB desktop limit. It will upload from a computer. To upload from your phone, export at a lower quality or as a JPG.
Does the checker work for Shorts thumbnails?
It recognizes vertical 9:16 images and checks them against the Shorts minimum height. See our Shorts thumbnail guide for how to set a custom Shorts thumbnail.
Is my thumbnail uploaded when I use this checker?
No. The image is read by your browser and never sent to a server. To get AI feedback on the design itself, use the ThumbRoasty analyzer on the home page.
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