YouTube thumbnail checker & AI rater
Drop in a thumbnail, paste one from your clipboard, or paste a YouTube link. The checker measures the image in your browser and tells you what to fix before you upload.
Check a thumbnail
How it looks where people see it
Greyscale shows whether it works on contrast alone; the blurred "squint" view shows what someone scrolling fast notices first.
AI rating
An AI critic judges what pixels can't: emotion, curiosity, how clear the idea is, and how well it fits your title. Free, a few per hour.
What the checker measures
| Check | What it looks at | Why it matters |
|---|---|---|
| Brightness | Average lightness | Dark thumbnails sink into the dark-mode feed; washed-out ones vanish on white |
| Contrast | Spread between light and dark | Separates the subject from the background |
| Colour pop | Colourfulness (Hasler–Süsstrunk) | Saturated accents draw the eye in a grid of other videos |
| Simplicity | How much of the image is fine edges | Detail turns into noise at 160 px wide |
| Feed-size punch | Contrast left after shrinking to 16 px wide | Whether big, bold shapes survive at the smallest sizes |
| Timestamp corner | Detail in the bottom-right corner | YouTube covers it with the video length |
The quick check measures pixels, not meaning: it can't tell whether the face shows the right emotion or whether the idea makes people curious. The AI rating judges those (clarity, emotion, contrast, text, curiosity and title fit) and lists concrete fixes.
FAQ
Is my image uploaded anywhere?
Not for the quick check: it runs in your browser. If you ask for the AI rating, a small copy (768 px wide) is sent to our AI critic for that one rating and is not stored.
What score should I aim for?
80 or more is strong. Popular thumbnails we tested scored 75–95; flat, dark or cluttered ones scored under 55. Use the individual checks to see what to fix.
Can I check a Shorts cover?
Yes. The measurements work for 9:16 images too; the size check will remind you that regular videos need 16:9.
Fix it with AI
Clickframe makes thumbnail concepts and images, adds crisp text, and scores the result.
Try Clickframe free