1280×720 every time. No guessing, no pixel math.
or drop an image here
JPG, PNG, WebP · Up to 15MB free
The problem
YouTube rejects thumbnails that aren't 16:9. You open Photoshop, guess the crop, export, upload, and it still looks wrong.
The fix
Upload your image. Select YouTube Thumbnail. See the result instantly. Download and upload to YouTube.