The Quora Space Image size (1280×720px)
A Quora Space is a topic-based community, and its header image is the banner that appears at the top of the Space and in the feed when the Space's content is surfaced. A 1280x720 pixel image in a 16:9 ratio is a solid choice: it is the familiar widescreen shape, wide enough to work as a banner and to display cleanly in the feed cards where Quora shows a Space alongside its questions and answers.
The main thing to design for is legibility at feed size and against the overlay. The header sits behind the Space name and follower details, and in the feed it is shown much smaller than full width, so a clear focal point and, if you use text, a short readable label work far better than a detailed graphic. Keeping the Space title or key subject within the central area helps it survive both the header overlay and any crop Quora applies when it slots the image into a narrower card.
Sizing to the native 16:9 frame at 1280x720 avoids the letterboxing and stretching that occur when an off-ratio image is forced into the banner. Because a Space header signals what the community is about at a glance, a clean image that matches your topic helps the right people decide to follow. This tool resizes 100% in your browser with no upload, it is free, and it preserves the 16:9 aspect ratio. Quora can update how it sizes and crops Space images, so verify the current spec before you set up or refresh your Space.