Profile photos and avatars
A 512×512 PNG is a practical starting point for most profile images. Center the eyes slightly above the middle, leave space around hair and shoulders, and remember that some apps add their own ring or status badge over the edge.
Team and staff directories
Use one output size and a consistent head-and-shoulders composition across the group. A subtle border can separate portraits from mixed page backgrounds, while a transparent edge lets each avatar sit naturally inside different layouts.
Logos and simple graphics
Choose PNG so transparent corners remain clean. Keep small lettering and thin marks away from the circular boundary, because a tight crop can make a logo look cramped or remove details that were designed for a square canvas.
High-resolution reuse
Export 1024×1024 only when the original has enough detail and you expect to reuse the image at larger sizes. You can always make a smaller copy later, but enlarging a low-resolution avatar usually makes edges and facial details softer.