Frequently Asked Questions

Upload 2–4 thumbnail images in the upload area at the top. Toggle the checklist items on each thumbnail card to calculate CTR scores automatically. Use the size preview tabs to see how your thumbnails look at actual YouTube display sizes, and compare which thumbnails perform best in the score summary table.

No, absolutely not. This tool operates entirely within your browser. It uses the FileReader API and URL.createObjectURL to process images locally. No image data is sent to any external server. Images are cleared when you close the browser tab.

The score is the sum of 5 checklist items, each worth 20 points: ①Text Readability (text is readable at small sizes), ②Color Contrast (sufficient contrast between background and elements), ③Face/Emotion (clear face or emotional expression), ④Whitespace (whitespace provides visual comfort), ⑤Brand Consistency (consistent with channel style). Check each item that your thumbnail satisfies.

Scores are reference values only. Actual CTR is influenced by many factors: content quality, topic interest, publication timing, YouTube's algorithm, and your channel's existing subscriber base. This tool is most effective as a relative comparison between two thumbnails rather than an absolute predictor.

YouTube recommends a 16:9 ratio, with a minimum size of 1280×720px and an ideal size of 1920×1080px. File size should be under 2MB. JPG, PNG, BMP, and GIF formats are supported. When this tool shows "Recommended" for the ratio, it means the thumbnail is 16:9.

Yes. "Face/Emotion" is one of 5 items worth 20 points, meaning you can still score 80/100 on the other four criteria. For product reviews, cooking, tutorials, and beauty content, a compelling before/after, product close-up, or striking result photo often achieves high CTR without a face.

Checklist scores are saved in your browser's localStorage and restored on your next visit with the same browser. Images themselves are not saved, and clearing browser data will reset scores. Nothing is stored on any server.

Yes — YouTube Studio has a "Thumbnail A/B test" feature that rotates two thumbnails on an uploaded video and compares CTR data. We recommend using this tool for pre-upload analysis, then validating your final choice with YouTube Studio's built-in A/B test.

Choose background and text/element colors that differ in both luminance (brightness) and hue. Combinations like yellow text on a white background have similar brightness and low contrast despite different hues. Use free tools like WebAIM Contrast Checker or Canva's color contrast feature to check WCAG standards.

You can compare up to 4 thumbnails simultaneously. If you have more than 4 candidates, compare 4 first, select the top 2, then compare those against new candidates. Refreshing the browser will reset the tool.