How to use it
- Click Choose a file and pick a picture, or drop it on the box.
- Choose the Radius unit: a percentage of the shorter side, or pixels.
- Move the Radius slider until the corners look right in the preview. The transparent part is shown over a chequered background.
- Click Download the PNG. The file keeps its transparent corners wherever you place it.
How the corners are made
Each corner is a quarter circle of the chosen radius. The page draws the picture only inside the outline made by the four corners, so the parts outside the outline are transparent. A percentage is taken of the shorter side of the picture; a pixel value is taken as it is. Either way the radius is cut to half the shorter side, so the corners never overlap.
The area the four corners cut away is (4 - pi) times the square of the radius. At a radius of half the shorter side of a square, the transparent area is 21.46 per cent of the picture: the four corners outside an inscribed circle. A square picture at 50 per cent therefore gives a round image with transparent edges, which is a circle crop with transparency.
Why the result is a PNG
A JPEG cannot store transparency, so a picture with rounded corners is saved as a PNG. The PNG keeps every pixel of the picture exactly. A photo is therefore larger than the same photo saved as a JPEG.
The page does not add a background colour. Where a background is needed, place the PNG on top of it in your editor or in the page that uses it.
Example: an 800 by 600 picture with a radius of 10 per cent
A radius of 10 per cent of the shorter side (600 pixels) is 60 pixels. The four corners then cut away (4 - pi) times 60 squared, which is 3,090.3 pixels of 480,000, or 0.64 per cent of the picture. The corners are small, so the change is subtle.
The same picture at the largest radius, 300 pixels (half the shorter side), has 16.1 per cent of its pixels transparent at the corners.
Frequently asked questions
Is my picture uploaded when I round its corners?
No. The picture is read by your browser, the corners are cut in the browser and the PNG is written on your device. You can check this by turning off your internet connection after the page has loaded and rounding a small picture.
Why is the download a PNG and not a JPEG?
The rounded corners are transparent, and a JPEG cannot store transparency. The PNG keeps the picture's pixels exactly, so the file is larger than a JPEG of the same picture.
What is the largest radius I can use?
Half the shorter side of the picture. At that radius the two corners on each short side meet, and a square becomes a circle. A larger value is cut to the half.
Should I use a percentage or pixels?
A percentage works for any size of picture and keeps the look the same when the picture is resized. Pixels give an exact radius, which is useful when a design needs one.
Can I make a circle profile picture with this tool?
Yes, for a square picture, set the radius to 50 per cent. The image crop tool on this site also makes a circle crop with a chosen area, which may suit a photo that is not square.
Sources
Figures and text last checked on Wednesday, November 11, 2026.