Check your thumbnail at YouTube’s real sizes
Your images and titles stay in this browser tab. Nothing is uploaded, nothing is stored, and nothing leaves your device.
Optional. Each title renders the way YouTube sets it for that surface, so you can judge the thumbnail and the title together.
A thumbnail that reads at 1280 pixels can disappear at 160. This tool renders yours at the sizes YouTube actually uses, from 500 pixels down to 148, plus a 72 pixel stress test, so you can judge it before you publish rather than after.
Why do small sizes matter more than the big one?
You design at 1280 x 720. YouTube almost never shows it that way. A search result gives you 500 pixels of width, the home feed 347, the suggested rail beside a video 220, and the home feed on a phone 160. Text that looked confident at full size turns into a gray smear, and the face you cropped so carefully becomes a smudge.
The 72 pixel tile is not a YouTube size at all. It is a stress test. Detail that survives 72 pixels survives anywhere, and detail that vanishes there was probably never doing any work.
Why check your thumbnail in grayscale?
Color does a lot of work, and it can hide a weak composition. Grayscale takes it away and leaves you with the thing underneath: value, contrast, and shape. If the subject still separates from the background with the color gone, the design is carrying itself. If everything flattens into one middling gray, the contrast was never there, and no amount of saturation will fix it.
Why are these sizes accurate at 100% browser zoom?
Every tile is drawn at its true width and never scales to fit. That guarantee depends on your browser sitting at 100% zoom. At any other zoom your browser scales the whole page, so a tile labeled 220 stops being 220 pixels of your actual screen, and the comparison quietly stops meaning anything. Reset the zoom before you judge a size.
The sizes themselves were measured off YouTube rather than estimated, logged out, in a real browser, at more than one window width. They are a snapshot of one day, and YouTube changes its layouts, so they are honest rather than eternal.
Does the rest of your work get this much scrutiny?
I build websites, run paid ads, and fix the search problems that quietly cost people work. Same habit of checking the thing at the size it is really seen.