Is the uploaded thumbnail sent to a server?
No. The image is read with browser APIs and analyzed locally. Shared links include the score and title, not the uploaded image.
Free YouTube Thumbnail Checker
Check your thumbnail before it goes live.
Upload up to 3 thumbnail variants, enter the video title, preview them in YouTube-style layouts, and get a local readiness score before publishing.
FreeNo sign-upPrivateBrowser-onlyUp to 3 variants
Images never upload
Upload a thumbnail
JPG, PNG, or WebP. Analysis stays in your browser.
Recommended YouTube thumbnail format: 1280 x 720, 16:9, under 2 MB.
Color analysis uses the open-source fast-average-color browser library.
Compare up to 3 variants without uploading thumbnails to a server.
Used locally for title rewrites. It is not uploaded.
Readiness score
--Upload first
The score combines YouTube format fit, contrast, sharpness, edge crowding, and title fit. It is a preview heuristic, not a CTR guarantee.
Why this score
ThumbAudit scores avoidable packaging risks before upload. It is a readiness check, not a guaranteed CTR prediction.
Format fit
22% weightChecks 1280 x 720, 16:9 framing, and YouTube-friendly file size.
Visual contrast
22% weightLooks for enough light and color separation to survive mobile feeds.
Sharpness
22% weightFlags soft screenshots, low-detail exports, and blurry focal points.
Title fit
18% weightChecks whether the video title can wrap clearly in YouTube previews.
Edge crowding
16% weightPenalizes busy borders where overlays, timestamps, and crops compete.
Preview lab
Compare how the thumbnail reads across common YouTube surfaces.
Desktop home feed
Upload a thumbnail
I redesigned my YouTube thumbnail and the click-through rate changed fast
Creator channel
48K views · 2 hours ago
Mobile preview
Upload a thumbnail
I redesigned my YouTube thumbnail and the click-through rate changed fast
Creator channel · 48K views
Publishing checklist
0 of 3 checks are ready.
Upload image
Waiting for thumbnail
Enter title
Preview wraps live
Review previews
Desktop, search, watch, mobile
Local title coach
Free title rewrites run locally. AI review can become the Pro layer.
Title fit99
Characters73/72 target
Suggested titles
I redesigned my YouTube thumbnail and the click-through rate...
I tested creator compares old against so you do not have to
Creator compares old against: what changed after the redesign
AI workflow signals
The free checker runs locally. These upgrade actions measure paid intent before model calls are enabled.
Run a thumbnail check first to make AI review and exports useful.
What the score checks
The checker looks at practical signals creators can fix before publishing: YouTube export format, visual contrast, image sharpness, edge crowding, and how the title wraps in previews.
Upload image
Ready in the first screen.
Enter title
Ready in the first screen.
Preview layout
Ready in the first screen.
Share result
Ready in the first screen.
Actionable fixes
Every suggestion is based on the uploaded image and title. The tool does not predict YouTube CTR; it catches avoidable preview problems before your audience sees them.
Use a 16:9 frame so the thumbnail does not crop oddly.
Make the subject readable at mobile feed size.
Keep large text short and away from busy edges.
Compare the thumbnail against the title before publishing.
YouTube thumbnail checker FAQ
What size should a YouTube thumbnail be?
YouTube recommends 1280 x 720 pixels, a 16:9 aspect ratio, and a file under 2 MB.
Does this predict CTR?
No. It is a readiness score for visible thumbnail issues. Actual CTR depends on audience, topic, packaging, and competition.
What does the score measure?
The score combines format fit, contrast, sharpness, edge crowding, and title fit so you can catch avoidable packaging problems.
Can I compare multiple thumbnails?
Yes. Upload up to 3 variants, select the active version, and the score, preview, checklist, and share link update locally.
Can I use it on mobile?
Yes. The upload control works on mobile browsers, and the preview includes a mobile feed-style frame.
Can I share the result?
Yes. Use Copy or Share after analysis to generate a result URL without uploading the image.
Does this replace YouTube A/B testing?
No. Use this as a pre-publish QA step. Live A/B tests are still useful when you need audience-backed experiment data.
Is this affiliated with YouTube?
No. YouTube is a trademark of Google LLC. This is an independent creator tool.