Round the corners of an image
Edited in your browser · the file is never uploaded
Rounds the corners of an image, up to a full circle at 50%. The corners are genuinely transparent, not painted white, so the result sits correctly on any background.
How to round the corners of an image
The corners are cut with a clipping path rather than filled with a colour, which is the difference between an image that works anywhere and one that only works on white. A filled corner looks fine on the page you designed it for and shows as an obvious white wedge on a dark background or a coloured card. Transparency has no such problem.
That is also why the output is PNG. JPEG has no alpha channel at all, so saving a rounded image as JPEG fills the corners with a solid colour: usually black, which is worse than the white you were trying to avoid. If a service insists on JPEG, the honest answer is that you cannot have rounded corners in the file and should round them in CSS instead.
A circle needs a square source. At 50% radius a non-square image becomes a stadium shape. Rounded ends on a rectangle: rather than a circle, because the radius is measured against the shorter side. Crop to 1:1 first if a circle is what you want.
Worth mentioning: for a profile picture you often do not need this at all. Almost every platform crops avatars to a circle in CSS, so uploading a plain square gets you the same result with none of the transparency handling. Rounding the file matters when the image will sit somewhere you do not control the styling: an email, a PDF, a slide.
Questions
The radius is measured against the shorter side, so a rectangle becomes a stadium shape. Crop to a square first.
Because these edits either keep transparency or create it, and JPEG has no transparency; it would fill those areas with black.
Genuinely transparent: cut with a clipping path, so the image sits correctly on any background.
Usually not. Most platforms crop avatars to a circle themselves. It matters for emails, PDFs and slides where you do not control the styling.
No. It is read into your browser, drawn to a canvas and read back. There is no server involved, which you can confirm by loading the page and then going offline.