Leave a Safe Margin Around the Subject
A common rule of thumb is to keep your main subject within roughly 80% of the frame's diameter, leaving the outer 10% on each side as a buffer. That margin absorbs minor repositioning later and guarantees that nothing important — the top of a head, the edge of a logo's wordmark — ends up sitting exactly on the circle's boundary, where it would look awkwardly clipped.
Center Optically, Not Just Mathematically
Mathematical centering (placing an object at the exact midpoint of the canvas) and optical centering (where an object looks centered to the human eye) are not always the same thing. Asymmetric shapes, like a face turned slightly to one side, or a logo with more visual weight on one edge, often need to be nudged a few pixels off true-center to read as balanced inside a circle. Trust your eye over the ruler here.
Watch Stroke Weight at Small Sizes
If you're designing an icon or logo that will eventually be circle-cropped down to a small avatar size, thin strokes and fine details tend to disappear or turn muddy once scaled down. Bold, simple shapes hold up far better at 32px or 48px than intricate line work does. If your design has fine detail, consider a simplified version specifically for small circular contexts.
Avoid Text Near the Edge
Text is the first thing to suffer in a circular crop, because letters near the corners of a square source image are exactly what gets sliced away. If your design includes a wordmark or label, keep it close to the vertical and horizontal centerlines, not tucked into a corner.
Check Contrast Against Real Backgrounds
Round icons and avatars get placed on all kinds of backgrounds — dark mode chat bubbles, light mode profile headers, colored brand banners. Before finalizing a design, preview it against a few different backgrounds to make sure it doesn't disappear or clash. A subtle outer ring or contrasting border can help a light icon stay visible on a light background.
Once your composition follows these guidelines, the actual circle crop becomes the easy part — a tool just needs to clip the corners, and everything you've already planned for will hold up.