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Thumbnail squint test

Most viewers see your thumbnail at 120 to 360 pixels wide for less than a second. The squint test shrinks your thumbnail to those sizes and lets you blur it, drain the colour, or simulate colour blindness, so you can check it still reads as one clear idea. Add a second thumbnail to compare them side by side.

Sample

Or paste or drop an image.

A second version to compare.

This is a sample so you can try the controls. Add a thumbnail above to test your own at the sizes viewers actually see.

Home feed (desktop) (360px wide)

Sample thumbnail at 360px12:34
Sample

Up next sidebar (168px wide)

Sample thumbnail at 168px12:34
Sample

Small phone list (120px wide)

Sample thumbnail at 120px12:34
Sample

What to look for

  • At the smallest size, can you still tell what the image is about in one second?
  • With squint on, is there one clear subject, or several things competing?
  • In greyscale, does the subject still stand apart from the background?
  • Does the length badge in the corner cover anything important?
  • Is any text still readable at 168px? If not, it's decoration, so the image has to carry the idea.

Your images stay in your browser. Nothing is uploaded.

How to use it

  1. Add one thumbnail, or two to compare.
  2. Turn up 'Squint' to blur both images equally.
  3. Turn on greyscale to check the subject stands out by brightness, not just colour.
  4. Try the colour vision options and check the length badge doesn't hide anything.

Questions

What is the squint test for thumbnails?

Designers blur their eyes, or the image, to see the main shapes and contrast. If a thumbnail still reads when blurred and small, it will usually read in a busy feed.

Why check a thumbnail in greyscale?

Greyscale shows whether your subject is lighter or darker than the background. Colour alone often isn't enough, especially for viewers with colour blindness.

How common is colour blindness?

Red-green colour blindness affects roughly 1 in 12 men and 1 in 200 women of Northern European descent, so a red-on-green thumbnail can lose a meaningful share of viewers.

Are my images uploaded?

No. Everything happens in your browser.

Last updated 2026-10-14.

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