Why transparency matters here
Rounding corners does not remove anything from the picture itself. It makes the area outside the rounded shape transparent, so whatever sits behind the image shows through. That is why the output has to be a PNG.
If it were saved as JPG, those corners would be filled with white instead. On a white page nobody would notice, but placed on a coloured background the image would show four white triangles around its edges.
Choosing a radius
A small radius reads as a subtle detail and suits photographs in a document or a slide. A large radius becomes a design statement. Somewhere around ten to twenty percent of the shorter side is where most interfaces sit.
The circle option takes this to its limit. For a circle to look right the image should be square, so crop to a one to one ratio first if it is not, otherwise the result is an oval.
Where this is useful
- Website avatars. A circular image ready to drop into a page without CSS.
- Presentations. Rounded photos look less harsh against a coloured slide.
- Documents and reports. Softened corners sit more comfortably alongside text.
- App mockups. Icons and thumbnails that match a rounded interface style.
Frequently asked questions
Why is the output a PNG?
The rounded areas have to be transparent so the image sits cleanly on any background. JPG has no transparency, so those corners would come out as white squares instead.
Will the file get larger?
Usually yes, since PNG stores every pixel exactly. For a photograph the increase can be significant, which is the trade for keeping transparent corners.
How do I make a perfectly round profile picture?
Choose the circle option. If your image is not square, crop it to a one to one ratio first, otherwise the circle becomes an oval.
Can I use this for a WhatsApp or LinkedIn photo?
Those platforms apply their own circular mask, so you do not need to round it yourself. This tool is more useful for websites, presentations and documents where no mask is applied.
Does the corner radius work the same on every image?
The radius is calculated as a share of the shorter side, so the result looks proportionate whether the image is small or large.
Can I get the square corners back?
Not from the output file, since those pixels are now transparent. Keep your original if you might want it unrounded.