Free Thumbnail Compare Tool

Thumbnail Compare for YouTube

Compare thumbnail variants side by side and choose the safest pre-publish option using local scores, mobile previews, title fit, and a shareable audit report.

Side-by-side variantsBest-score flagTitle fitMobile previewPrivateMarkdown report
Images never upload

Upload a thumbnail

JPG, PNG, or WebP. Analysis stays in your browser.

Use a 16:9 thumbnail. ThumbAudit treats 1280 x 720+ as preview-ready and flags 2 MB as the mobile-safe copy target.
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.

Why this score

ThumbAudit scores avoidable packaging risks before upload. It is a readiness check, not a guaranteed CTR prediction.

Local QA

Format fit

22% weight

Checks 16:9 framing, HD-or-better export, and mobile-safe file size.

Visual contrast

22% weight

Looks for enough light and color separation to survive mobile feeds.

Sharpness

22% weight

Flags soft screenshots, low-detail exports, and blurry focal points.

Title fit

18% weight

Checks whether the video title can wrap clearly in YouTube previews.

Edge safety

16% weight

Penalizes busy borders where overlays, timestamps, and crops compete.

Mobile readability

Checks the small-screen risk created by contrast, softness, title wrapping, and crowded edges.

Local
Mobile fit0
Upload a thumbnail to check whether the subject survives mobile size.
Keep large text short, high contrast, and away from the lower corners.
Use the mobile preview before choosing the final variant.
Publishing checklist

0 of 3 checks are ready.

45%

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.

99/100
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.

Free + Pro

Run a thumbnail check first to make AI review and exports useful.

Improve with AICreative review, title rewrites, and stronger hooks.ProCompare variantsJudge multiple thumbnail options before publishing.ProBatch reportsPackage client-ready reports across many thumbnails.Studio

What the score checks

The checker looks at practical signals creators can fix before publishing: YouTube export format, visual contrast, image sharpness, mobile readability, edge safety, variant comparison, 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.

Check safe area

Ready in the first screen.

Share result

Ready in the first screen.

Export report

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.

Related thumbnail tools

Each entry opens the same local checker with a different pre-publish workflow: preview, test, compare, score, or audit.

YouTube Thumbnail Preview

Check mobile, desktop, search, and watch layouts.

YouTube Thumbnail Tester

Compare variants before publishing.

Thumbnail Compare

Review side-by-side scores and decision risk.

Thumbnail Score

Understand readiness, readability, and safe-area risk.

Thumbnail Audit

Export a pre-publish report for review.

YouTube thumbnail checker FAQ

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.

What size should a YouTube thumbnail be?

Use a 16:9 image. ThumbAudit treats 1280 x 720 or larger as preview-ready and flags 2 MB as a mobile-safe upload copy target.

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, mobile readability, edge safety, 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.