YouTube thumbnail previewer — test it before you upload

Why test a thumbnail in context

A thumbnail is never seen alone. On the home page it sits between eleven other videos; in the sidebar it shrinks to roughly the size of a matchbox. Something that looks great full-screen in your design app can turn into a blur of small text once it's 168 pixels wide.

Seeing it surrounded by other videos answers the only question that matters: would you notice it while scrolling? If your eye goes to the neighbours first, the thumbnail needs more contrast, a bigger subject or fewer words.

What to look for in each layout

Home grid: does the subject read from a distance, and does the timestamp in the bottom-right corner cover anything important? Search: your title gets more room here, so the thumbnail can carry an image instead of repeating the title. Up next: at the small size, check that faces and the one or two key words still read. Phone: most views happen here; test in dark mode too, because thin white borders and dark backgrounds behave differently.

If you're comparing A, B and C, look at the small strip first. The option that still makes sense at that size usually wins at every size.

Thumbnail size and format

According to YouTube Help, thumbnails should be 16:9 with a minimum width of 640 pixels, in JPG or PNG (the full numbers are in our YouTube size guide, with the date they were checked). The previewer crops anything that isn't 16:9 the way the feed does, so you'll spot cut-off text before your audience does.

No face on camera? Use a character

Faceless channels still benefit from a face in the thumbnail. Our talking characters come with seven expressions — surprised, serious, thinking and more — that you can screenshot from the studio and drop into your thumbnail, so the same host appears in the video and in the feed.