60% of YouTube traffic is mobile. Thumbnails that look fine on desktop often become unreadable on a 4-inch phone screen - tiny text, low contrast, busy backgrounds all fail. Our mobile preview shows your thumbnail at the actual size it renders on iPhone and Android YouTube apps.
When to use this
Use for: testing thumbnails before publishing to ensure they work on mobile, A/B testing two thumbnail options to see which holds up at small sizes, post-mortem on low-CTR videos (was the thumbnail unreadable on mobile?).
Frequently Asked Questions
What size does YouTube show thumbnails at on mobile?
Roughly 160x90 pixels in the home feed, 320x180 in search / watch-page recommendations. Both are much smaller than the 1280x720 source - so design with the assumption that the thumbnail will be tiny in practice.
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