Thumbnail Text Readability Checker

Creators judge a thumbnail on a big editor canvas where every word is crisp, then publish it into a phone feed where it's a 168-pixel-wide smudge next to a dozen competitors. Text that felt punchy at full size routinely turns to mush at feed size, and the only signal you get is a quietly low click-through rate days later — long after you could have caught it.

This checker downsamples your thumbnail to the real feed size, blurs it the way scaling and compression do, and scores contrast and detail density so you find out before you publish, not after. Pair it with the Thumbnail Preview tool to see the same image across every YouTube surface at once and confirm it holds up everywhere.