Test your thumbnail before you publish
Instant 0-100 score · Real feed previews · Free, no signup · Your image never leaves your browser
Why creators use it
Eleven deterministic checks (brightness, contrast, sharpness, clutter, text amount, face size and more) roll up into one 0-100 score with prioritized fixes.
Preview your thumbnail in the YouTube home feed, suggested sidebar, mobile app and search results, in light and dark mode, before you publish.
Analysis runs entirely in your browser, including the face and text detection models. Your thumbnail is never uploaded to a server.
About the thumbnail analyzer
Most thumbnails are judged at full size on a big editing monitor, but viewers see them at 168 pixels wide, sandwiched between competitors, usually in dark mode. This tool scores your thumbnail the way the feed treats it: it measures brightness, contrast, saturation and sharpness; counts words and checks whether the text stays readable at sidebar size; detects faces and how much of the frame they fill; and flags anything sitting under YouTube's duration badge.
Every check is a deterministic measurement, not an AI guess, so the same image always gets the same score, and every recommendation tells you the measured value and the winning range. When you've made changes, re-upload and watch the score move.
New to thumbnail design? Start with our 9-point YouTube thumbnail checklist for the exact rules behind each score.
Frequently asked questions
Is this thumbnail analyzer really free?
Yes. There's no account, no credits, and no watermark. It's supported by ads, just like our other tools.
Is my thumbnail uploaded anywhere?
No. Every check, including face detection and text recognition, runs inside your browser. The image never leaves your device.
What does the score mean?
It's a weighted blend of four groups: technical requirements, visual impact, clarity, and subject. 75+ is strong; below 50 means the prioritized recommendations list has critical fixes for you.
What size should a YouTube thumbnail be?
1280×720 pixels at a 16:9 aspect ratio, and the file must be under 2 MB. The analyzer checks all three automatically.
Why is the first analysis slower?
The first run downloads the in-browser face and text detection models (a one-time step). They're cached afterwards, so repeat analyses finish in a couple of seconds.
Does it work for Shorts or other platforms?
The checks target standard 16:9 YouTube thumbnails. Most visual metrics (brightness, contrast, clutter, text) are still useful for any platform's cover image.
Need to fix the thumbnail before testing it? Remove the background, upscale a soft source, or compress it under YouTube's 2 MB limit. All free, all in your browser.