Free YouTube Thumbnail Tester
See your thumbnail exactly where viewers decide to click — the home feed, a phone, search results and the tiny up-next list — and check it against YouTube's current size rules. Free, no sign-up, nothing uploaded.
Home feed · computer
I Tried the Viral Thumbnail Trick for 30 Days
Your Channel
48K views · 2 days ago
Phone feed
I Tried the Viral Thumbnail Trick for 30 Days
Your Channel · 48K views · 2 days ago
Search results
I Tried the Viral Thumbnail Trick for 30 Days
48K views · 2 days ago
Your Channel
Up next · smallest size (168 px wide)
I Tried the Viral Thumbnail Trick for 30 Days
Your Channel
Can you still read the text and see the subject here? If not, simplify.
Showing a sample thumbnail. Drop your own image to see it in the feed.
YouTube thumbnail requirements (2026)
Taken from YouTube's own help center, updated for the new 4K recommendation.
| Thumbnail | Recommended size | Ratio | Minimum |
|---|---|---|---|
| Video | 3840×2160 | 16:9 | 640 px wide |
| Shorts | 2160×3840 | 9:16 | 640 px high |
| Podcast playlist | Square | 1:1 | — |
File size: up to 50 MB from a computer, 2 MB for video thumbnails from a phone (10 MB for podcasts). Formats: JPG or PNG. Custom Shorts thumbnails can currently only be added in YouTube Studio on a computer, and custom thumbnails need a verified account.
Want the full guide? Read YouTube thumbnail size, format and safe zones or how to A/B test thumbnails.
Thumbnail tester FAQ
Thumbnail not quite there yet?
Describe your video and let ThumbMagic design one built for the feed — in 16:9 up to 4K, with a Shorts cover included. Your first one is free.