How should I rate readability honestly?

Switch the preview to Small (180px wide). That's roughly the size of a thumbnail in YouTube search results on a phone. If you can read every word at that size, give it 8–10. If you squint, 5–7. If words blur together, under 5.

What counts as a high 'face visibility' score?

A clear, expressive face that takes up at least a third of the frame and is making eye contact with the camera. No face or a tiny background face is 0–3. A clear medium-shot face is 7–10.

Can I compare more than two thumbnails?

Not in this tool. For 3+ variants, run successive A/B comparisons and note the winners. A future version may add multi-variant support.

Are my images uploaded anywhere?

No. Files are read with URL.createObjectURL() and stay in your browser's memory. Closing the tab or clicking Reset revokes the URLs and discards the data.

Content Creator Tools

Thumbnail A/B Comparer

Upload two thumbnail images and compare them side by side at full, medium, and small sizes on either a dark or light background. Rate each on text readability, face visibility, contrast, and curiosity — the scorecard updates live and picks a winner.

Your file is processed locally in your browser. It is not uploaded to Dueneo.

Loading Thumbnail A/B Comparer…

How to use

1
Upload both thumbnails
Drag each image into its upload zone (or click to browse). Files are loaded as object URLs and never leave your browser.
2
Toggle preview size and background
Switch between Full, Medium, and Small to see how each thumbnail holds up at phone sizes. Toggle the dark background to test legibility on dark mode.
3
Rate each criterion 0–10
Move the sliders for text readability, face visibility, contrast, and curiosity. Use the small-size preview to judge readability honestly.
4
Read the verdict
Totals update live and the winning thumbnail is highlighted. The Edge column shows which side won each criterion.

Common use cases

Pick the higher-CTR variant before running a YouTube thumbnail test.
Audit your existing thumbnail against a redesigned version.
Teach a team member what makes a thumbnail readable at small sizes.
Compare thumbnail treatments across light and dark mode.

Limitations

The scorecard is a structured self-review — the scores are your own ratings, not an automated ML prediction. Use it to force a deliberate comparison, not as ground truth.
The 16:9 aspect ratio is hard-coded to match YouTube thumbnails (1280×720). Instagram reels, TikTok and Shorts use 9:16 — use a different tool for those.
Images are loaded as blob: URLs and never uploaded. Closing the tab revokes the URLs and frees the memory.
Maximum image size is 10 MB per file. Larger files slow down the preview and can crash low-memory devices.

Frequently asked questions

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Loading Thumbnail A/B Comparer…

How to use

Upload both thumbnails

Drag each image into its upload zone (or click to browse). Files are loaded as object URLs and never leave your browser.

Toggle preview size and background

Switch between Full, Medium, and Small to see how each thumbnail holds up at phone sizes. Toggle the dark background to test legibility on dark mode.

Rate each criterion 0–10

Move the sliders for text readability, face visibility, contrast, and curiosity. Use the small-size preview to judge readability honestly.

Read the verdict

Totals update live and the winning thumbnail is highlighted. The Edge column shows which side won each criterion.

Limitations

The scorecard is a structured self-review — the scores are your own ratings, not an automated ML prediction. Use it to force a deliberate comparison, not as ground truth.
The 16:9 aspect ratio is hard-coded to match YouTube thumbnails (1280×720). Instagram reels, TikTok and Shorts use 9:16 — use a different tool for those.
Images are loaded as blob: URLs and never uploaded. Closing the tab revokes the URLs and frees the memory.
Maximum image size is 10 MB per file. Larger files slow down the preview and can crash low-memory devices.