The YouTube Community Post size (1080×1080px)
YouTube community posts let creators share images, polls, and updates with subscribers between videos, and a 1080x1080 pixel square at 1:1 displays cleanly in both the community tab and the subscription feed. The square format keeps your image fully visible without the aggressive cropping that off-ratio images can trigger in the feed.
Community posts are a great place for behind-the-scenes shots, video teasers, poll graphics, and announcements. Because they appear in a feed alongside text, a clean 1:1 image with a clear focal point works better than a busy collage, and a square shape reads consistently whether viewed on the web community tab or in the mobile app.
If you add text to the image, keep it centered and large enough for mobile, since many subscribers see community posts on phones. Avoid placing critical wording at the extreme edges in case a placement crops slightly, and upload at the full 1080x1080 so your image stays crisp rather than getting softened by upscaling on larger screens.