YouTube thumbnail size in 2026: why you may see both 3840×2160 and 1280×720.
Those numbers describe different things. YouTube's current Help guidance recommends a larger source image for custom thumbnail uploads, while the Data API documents a 1280×720 maxres thumbnail rendition.
The short answer
For a new custom thumbnail you are uploading, YouTube currently recommends 3840×2160 pixels, with a minimum width of 640 pixels, and says creators should try to use a 16:9 aspect ratio for normal video thumbnails.
Separately, YouTube's Data API documentation lists common video thumbnail renditions: 120×90 default, 320×180 medium, 480×360 high, 640×480 standard for some videos, and 1280×720 maxres for some videos.
Why the two size recommendations are not a contradiction
The upload recommendation describes the image you provide to YouTube. The API dimensions describe thumbnail images YouTube makes available for a video resource. An uploaded source can therefore be larger than the public thumbnail rendition a tool later retrieves.
Which size should a creator design?
If you are preparing a custom thumbnail today, follow YouTube's current upload guidance rather than designing around a downloader's output size. Use a high-quality 16:9 source image, keep important text and faces away from edges, and preview the design at a small size before publishing.
Why does maxres sometimes fail?
The Data API documentation says standard and maxres are available only for some videos and resources. A video can therefore have working default, medium or high thumbnails even when the maximum-resolution URL is unavailable.
What about vertical videos?
YouTube's Help page notes that vertical videos using a 16:9 custom thumbnail can show an automatically generated 4:5 thumbnail on some mobile discovery surfaces, while the custom thumbnail can still appear in other locations. That is another reason not to assume one thumbnail rendition is used everywhere.
Can you reuse another creator's thumbnail?
A publicly reachable thumbnail URL does not automatically give you permission to reuse the artwork. Use images you own, have permission to use, or can lawfully reuse under the rules that apply to your situation.
Primary sources for thumbnail dimensions
This guide was checked on August 25, 2026 against YouTube's official custom thumbnail Help page and Google's YouTube Data API thumbnail documentation.
YouTube thumbnail size FAQ
Is 1280×720 still a YouTube thumbnail size?
Yes. Google's Data API documentation currently lists 1280×720 as the maxres video thumbnail size when that rendition is available.
Should I upload only 1280×720?
YouTube's current custom-thumbnail Help page recommends 3840×2160, so follow the current upload guidance when creating a new source thumbnail.
Why does a downloader show several versions?
YouTube resources can expose multiple thumbnail renditions for different display needs. Not every video has every size.