The Discord Server Icon size (512×512px)
Discord recommends a 512x512 pixel image for server icons, and the square 1:1 source is important because Discord crops every server icon into a circle. That means the corners of your square get clipped, so any logo, letter, or symbol needs to sit within the central circular area or it will be cut off in the server list where members identify your community at a glance.
At 512x512 the icon has enough resolution to stay crisp across every place Discord shows it, from the tiny circle in the left server rail to larger previews in invites and the server overview. Discord downscales your image for the small sizes, so starting at 512 gives the app clean pixels to work from and avoids the fuzziness that comes from uploading something too small. It is the size Discord itself suggests for a reason.
Because the icon appears mostly at small sizes, simplicity wins: a bold monogram, a single clear symbol, or a high-contrast logo reads far better than a detailed illustration that turns to mush in the server rail. Keep strong contrast against both light and dark Discord themes, and center the mark so the circular crop frames it neatly. Everything here resizes 100% in your browser with no upload and for free, so your artwork stays on your device. Discord occasionally updates its icon handling and recommended sizes, so verify the current spec before finalizing your community branding.