Upload 2-4 thumbnails and compare them at real YouTube sizes. Get a contrast score for each and see which one is most likely to get clicks. All processing happens in your browser — images never leave your device.
High contrast, a clear focal point, readable text (if any), and emotional facial expressions tend to perform best. Your thumbnail must be readable at tiny sizes (168x94 on mobile sidebars) to compete in recommendation feeds.
The contrast score measures the range of brightness values in your thumbnail. Higher scores (70+) mean your thumbnail has bold lights and darks that stand out. Lower scores (under 40) suggest a flat image that may blend into the YouTube interface.
Yes — thumbnails that overpromise and under-deliver hurt watch time and long-term channel health. The best thumbnails create curiosity about what's actually in the video, not misleading clickbait.
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