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 looks good at 1920 pixels can look bad at 160. This tool renders your thumbnails at the sizes YouTube actually uses, from 500 pixels down to 148, plus a 72 pixel stress test, so you can judge your thumbnail at even the smallest size before you publish it.
Why do small sizes matter more than the big one?
You design at 1920 x 1080 or higher. YouTube almost never shows it that way except on TVs. A search result returns a thumbnail at 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 clear at full size turns into an ambiguous 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 shows up at 72 pixels can be seen anywhere, and detail that vanishes there was probably never going to be seen anyway. This helps you see if details you care about disappear or stay prominent.
Why check your thumbnail in grayscale?
Color is important to a good design, but it can hide a weak composition. Grayscale takes color away and leaves you with what's underneath: value, contrast, and shape. If the subject still separates from the background with the color gone, the design is well-composed and clear. If everything flattens into one middling gray, there wasn't as much contrast as you might've thought, and no amount of saturation will fix it.
What is the difference between the three conversions?
"Luminance" is the plain reading. It weights red, green, and blue the way the eye weights them, so what is left is brightness alone. It's closest to how your thumbnail looks once color is removed from the equation.
"Red filter" and "Blue filter" weight the same image in opposite directions. "Red filter" brightens warm areas and darkens cool ones, so warm skin lifts away from a cool sky. "Blue filter" does the reverse, brightening cool areas and darkening warm ones, so a cool subject lifts away from a warm background. Skin and a blue sky can flatten into a single gray under "Luminance," so if you need a more accurate read of how your thumbnail's contrast is perceived, use one of these filters. Both are included so warm and cool compositions can be both fairly judged.
"Red filter" is based on the "High Contrast Red Filter" preset in Photoshop, and "Blue filter" on "High Contrast Blue Filter." Both do the best they can to match the Photoshop preset. The conversion runs in your browser with a color matrix, though, so the result is a close stand-in for the preset, not a replacement for 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 set to 100% zoom. At any other zoom your browser scales the whole page, so a tile labeled 220 stops being 220 pixels of your screen, and the comparison loses its meaning. Reset the zoom before you judge a size.
The sizes themselves were measured on YouTube rather than estimated. The measurements were taken while logged out in a browser, at multiple window widths. They are a snapshot of one day, but we all know YouTube changes its layouts every now and then, so these sizes may change.