Thumbnail Lab
A thumbnail gets less than a second to earn the click.
Upload your thumbnail and Retensis reads it the way someone scrolling at speed would: what your eye lands on first, whether the text survives at feed size, whether the face and the subject compete, and what a viewer actually understands in the moment before they scroll past. You get specific changes, not a score you have to interpret.
No credit card required · 2 free analyses per month
Any image
Upload or paste
Feed size
Read as viewers see it
All plans
Included on Free
The Glance Test
Your thumbnail is judged at a size you never design it at.
You design at full size, on a bright screen, already knowing what the video is about. Your viewer sees it small, in a crowded feed, knowing nothing. Thumbnail Lab closes that gap by reading the image cold and reporting what survives the shrink: the focal point, the legibility of every word, the contrast between subject and background, and whether the promise is clear without the title.
Your thumbnail is judged at a size you never design it at.
What You Get Back
Specific changes, not a grade.
A number tells you something is wrong. It does not tell you what to move. Every finding names the element and the fix, so you can act on it in the editor you already have open.
- Where the eye lands first, and whether that is the thing you wanted
- Text that stops being readable at feed size
- Faces and expressions, and whether emotion reads clearly
- Contrast, clutter, and the elements competing for the same attention
- Whether the thumbnail and the title promise the same thing
Strong performance
Improve hook and audio for an A.
Compare Before You Publish
Pick between options instead of guessing.
Most creators have two or three thumbnails they cannot choose between. Read each one and compare what they actually communicate rather than which one you prefer after staring at both for ten minutes. The one you designed last is usually the one you like most, and that is a bias, not a signal.
Opening 3 seconds lack a pattern interrupt.
Current hook
“So here's my morning routine…”
Suggested hook
“Stop waking up tired. This changed everything.”
Part of the Whole Video
A click you win and then lose is not a win.
A thumbnail that oversells gets the click and loses the viewer in the first seconds, and short-form platforms notice. Pair Thumbnail Lab with your video analysis so the promise on the outside matches what happens on the inside, and the attention you earn is attention you keep.
2 free
analyses per month
No
credit card required
< 90s
analysis turnaround
FAQ
Common questions
No. Thumbnail Lab works on its own, so you can test an image before the video is finished or even filmed. If you have analyzed the video too, the read is more useful, because Retensis can tell you whether the thumbnail promises what the video delivers.
Every plan, including Free. There is no separate limit for thumbnails.
Both. A YouTube thumbnail and a TikTok or Reels cover are judged the same way by a scrolling viewer: at small size, in under a second, against everything around it. Retensis reads for that moment rather than for a full-screen view.
Ready to make your next video your best one?
Get scores, timestamps, rewrites, and a full content strategy. All in 90 seconds. Free to start.
No credit card required · 2 free analyses per month · Upgrade anytime