YouTube Thumbnail
Tester

The score is an Estimate — we call it that deliberately. It blends deterministic image analysis (contrast, palette diversity, edge density) with a GPT-4o-mini vision rubric that judges focal point, text readability at 168×94 mobile size, and colour appeal. It cannot predict your real CTR because that depends on your title, your audience, and the specific video — but it is a reliable second opinion on the thumbnail itself.

Yes. Upload up to 5 thumbnails per day per IP for free, no sign-up. Sign up for the paid Thumbnail Maker for unlimited scoring plus AI-generated thumbnails that score higher out of the gate.

JPEG, PNG and WebP up to 5 MB. Any aspect ratio works but 16:9 (1280×720 or 1920×1080) gives the most accurate mobile-preview judgement since that is the actual YouTube thumbnail size.

No. The image is scored in memory and discarded at the end of the request. We never save your uploads.

0-40 is Low — the thumbnail is likely to underperform and the reasons will point to what to fix. 41-70 is Good — solid but has room to grow. 71-100 is Strong — the composition, contrast and focal point all check out.

Try the paid Thumbnail Maker in the TubeWizz app — it generates three variants per prompt with GPT-4o image, factors in your brand colour and any style reference channel, and every variant comes with its own clickability score built in.