YouTube Tools
A/B Thumbnail Compare
Upload two thumbnail candidates to see them side by side at the sizes they really appear.
What this is
An A/B thumbnail compare shows two candidate images side by side at several display sizes, so you can judge which is stronger before committing. What makes it useful is the sizing: thumbnails are almost always judged large on an editing screen, while viewers see them at thumbnail scale on a phone. An image that reads clearly at 1280 pixels often loses all its meaning at 168 — and only a small-size comparison reveals that.
How it works
This is a static comparison, not a live test. What it tests is your own judgement of two images at real size, not how an audience reacts. Measuring actual viewer behaviour requires YouTube's own thumbnail test feature, which rotates candidates in front of a real audience.
Three things usually decide it at small size: whether the subject still reads, whether the text still reads, and whether the image still stands apart from the thumbnails around it. Viewing both in greyscale helps too — if they become similar without colour, the difference may rest on colour alone.
How to use it
- Upload two candidates Pick two thumbnail images. Both are processed on your device and uploaded nowhere.
- Compare at small sizes Focus on the mobile row — that is where most viewers actually see it.
- Try greyscale If the two become similar without colour, the difference rests on colour alone.
Common questions
- Does this run a real A/B test?
- No — it places two candidates side by side for your own judgement rather than testing audience reaction. Testing that measures real viewer behaviour is available through the thumbnail test feature in YouTube Studio, which rotates candidates in front of a live audience and reports the winner.
- What size should a YouTube thumbnail be?
- The recommended size is 1280 × 720 pixels at a 16:9 ratio, with a 2 MB file limit. Despite uploading at that size, thumbnails are nearly always shown far smaller — around 168 pixels in the suggested column — so legibility when small matters much more than sharpness at full size.
- Are my images uploaded to a server?
- No — both images are read directly by your browser and never transmitted anywhere. Closing the tab clears them from memory entirely.
Notes
- Images are processed in the browser and never uploaded.
- EnSaveNet is not affiliated with YouTube.