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Free Thumbnail Compare Tool

Thumbnail Compare for YouTube

Compare thumbnail variants side by side using local rules, mobile previews, title fit, and a practical audit report. The highest local score helps identify fixable risks; it does not predict which image an audience will click.

Side-by-side variantsHighest local scoreTitle fitMobile previewPrivateMarkdown report
Local checks never upload

Upload a thumbnail

JPG, PNG, or WebP. Rule checks stay in your browser.

Your pre-publish check

Not analysed

Upload an image or open the demo. Your score and first practical fix will appear here.

Local rules, not CTR or an audience A/B result.

Image guidance & local processing

Use a 16:9 frame. The local rules treat 1280 × 720+ as preview-ready and 2 MB as a mobile-safe copy target. Analysis accepts static JPG, PNG, or WebP up to 10 MiB (10,485,760 bytes) each, 8,192 pixels per side, and 16,777,216 pixels total. These are ThumbAudit processing limits, not YouTube upload restrictions.

Canvas and fast-average-color run in your browser. Images and video context are not sent to audit history.

Used locally for title rewrites. Sent only if you explicitly consent to optional AI review below.

Optional private audit

Analysis is free without an account. Only clicking Save private audit sends a snapshot to your account. Signing in, checking, sharing, or exporting never saves it for you.

Exactly what is sent

Video title; candidate labels, scores, dimensions and file sizes; preview surface and theme; readiness checks and fixed rule suggestions. The server uses your signed-in account and a request ID to save this snapshot once.

Never sent to audit history: image bytes, video context, context-based title ideas, AI feedback, or the share URL. History cannot restore your images. A full reload requires selecting them again.

Measure on YouTube ↗
Run a local check first. Nothing has been saved.

Optional AI creative review

Get qualitative feedback on the selected thumbnail, title and video promise. This does not change your local scores, predict CTR or run an audience A/B test.

What leaves this tab, limits & privacy

Only after consent and the review button: a white-backed, metadata-stripped JPEG copy (up to 1024 pixels per side, 600,000 pixels and 384 KiB), your current title and optional video context go to our server, then to KIE if both safety checks allow it. Animated images are not eligible. The original file stays local.

KIE is an external processor. Its retention and deletion policy has not been independently verified. Do not submit private or sensitive material. The initial safety policy is uncalibrated and can make mistakes; unknown results never bypass it.

1 request per account per UTC day, also subject to a site-wide allowance. Server failures or uncertain completion can consume a reservation. A direct retry of the unchanged snapshot keeps its request ID and exact JPEG. Editing the image, title or context starts a new snapshot and discards the previous cached copy; switching accounts also releases it. Feedback stays in this tab and is not added to private history, shared links or report exports. Reloading loses it.

KIE · GPT 5.6 Luna. Availability means configuration-ready only, not a verified model response or available provider balance. Usage can incur provider charges.

Optional AI review consent
Checking AI review availability. No image or text is sent.
Why this score

ThumbAudit scores avoidable packaging risks before upload. It is a five-input readiness heuristic, not OCR, AI creative review, or a CTR prediction. Review the image and video promise yourself.

Local QA

Format fit

22% weight

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

Visual contrast

22% weight

Estimates global light and color separation from sampled pixels; it does not identify a foreground subject.

Sharpness

22% weight

Estimates global edge detail from a small Canvas sample; it does not locate or evaluate individual subjects.

Title fit

18% weight

Uses title length and capitalization rules. Inspect the actual wrapping in the illustrative previews.

Edge safety

16% weight

Uses variation in border pixels as a crowding hint; it does not detect faces, text, or exact overlay collisions.

Mobile readability

A derived heuristic: 34% contrast, 26% sharpness, 20% edge safety, and 20% title fit. It does not read text or identify subjects.

Not analysed
Mobile fitNot analysed
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

Not analysed. Upload an image or try the demo to start.

Not analysed

Upload image

Waiting for thumbnail

Enter title

Preview wraps live

Review previews

Desktop, search, watch, mobile

Local title coach

Fixed title templates and length checks run locally. These are not AI suggestions or a review of the thumbnail's meaning.

100/100
Title fit100
Characters65/72 target
Suggested titles
A practical guide to clearer YouTube thumbnails before publishing
I tested creator compares old against so you do not have to
Creator compares old against: what changed after the redesign
What you can do today

The checker, 3-candidate comparison, and local export are free. External AI review is a separate, optional step with sign-in and consent. Neither provides CTR predictions or a live audience test.

Free tools

Run a check to compare candidates, inspect fixes, and export a report.

Compare 3 candidatesFree local comparison, not an audience experiment.
Export a local reportFree Markdown summary of your current checks and fixes.
Optional private audit historyOnly the metadata you explicitly choose to save.
View private audit history

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.

Thumbnail Compare for YouTube FAQ

What should I compare between thumbnails?

Start with mobile readability, contrast, subject clarity, safe-area risk, title fit, and whether the thumbnail still works in search and watch-sidebar layouts.

Does the highest score always win?

No. The score is a decision aid, not a guarantee. Use it to catch avoidable risks, then choose the variant that best matches the video promise.

Are uploaded thumbnails sent to a server?

Local checks do not upload your image or context. Save private audit sends only the listed audit metadata, not images or context. The separate optional AI review requires sign-in and explicit consent: it sends a smaller JPEG copy, the title, and any context you entered to our server for checks and then to KIE if allowed. AI results are not automatically added to saved history.

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 ThumbAudit predict CTR?

No. ThumbAudit provides a readiness score for visible thumbnail and title issues. Real CTR depends on audience, topic, packaging, and competition.