YouTube thumbnail size
The duration badge sits bottom right — keep it clear.
Cropped in your browser · your image is never uploaded
1280 × 720, 16:9, under 2 MB. YouTube accepts a minimum of 640 wide, but 1280 is the standard because it is what gets served on a desktop watch page.
How to use the youtube thumbnail size
The number that matters is not 1280 — it is 168. That is roughly how many pixels wide a thumbnail is in the mobile search results where most views actually begin, and it is the size your design has to work at. Three or four words is the practical ceiling for legible text; a sentence is unreadable. Two other things get in the way: the duration badge sits over the bottom-right corner, and on the watch page a red progress bar covers the bottom of a previously-watched thumbnail. Keep both corners clear of anything you need seen.
Questions
1280 × 720 pixels, 16:9 aspect ratio, under 2 MB.