CSS Border Radius Generator

Who Uses a Border Radius Generator and Why

Front-end developers reach for a border-radius generator when a button, card, or chat bubble needs corners that feel right but the shorthand values are hard to eyeball. Rather than tweaking numbers in the DevTools and reloading, they drag four sliders and copy the result. Designers use it to translate a mockup's rounded shape into the exact CSS a developer can paste into a stylesheet with no ambiguity.

Marketers and no-code builders use it too, since most email builders, Notion embeds, and website builders accept raw CSS in a custom style field. A landing page owner can round the corners of a hero image or CTA button in five seconds without touching a design tool. The tool works for anything that renders a rectangular box in HTML.

Common Border Radius Patterns

• Pill button: border-radius: 999px makes both ends fully round no matter the button width.
• Card: 12 to 20 pixels on all four corners for a soft, modern look that doesn't fight the content.
• Chat bubble: three large corners plus one small corner near the tail, like 18px 18px 18px 4px for a left-side bubble.
• Circle avatar: border-radius: 50% on a square element produces a perfect circle at any size.
• Squircle: elliptical mode with a horizontal radius bigger than the vertical produces a smoother iOS-style shape.

How the Border Radius Shorthand Works

The shorthand accepts one to four values, applied clockwise starting from the top-left corner: top-left, top-right, bottom-right, bottom-left. Skipped values are mirrored across the shape, so border-radius: 10px 20px means 10 for the top-left and bottom-right, and 20 for the top-right and bottom-left. The tool always outputs the explicit four-value form so behavior is unambiguous whichever way you paste it in.

Elliptical mode adds a slash and four vertical values. So 40px 20px 40px 20px / 30px 15px 30px 15px gives each corner a horizontal and vertical radius, which draws an oval curve instead of a circular one. That is the trick behind squircles, hand-drawn-looking cards, and organic shapes that would otherwise need SVG.

Border Radius Values by Element Type

Common Mistakes and Tips

The most common mistake is rounding a container that contains an image or video and finding the media leaks over the rounded corners in some browsers. Fix it by adding overflow: hidden to the rounded container, or by giving the media the same border-radius directly. The second common miss is using pixel values on elements that resize, which produces bigger visual rounding on small buttons and near-square edges on huge ones. Use percentages or the 999px pill trick when the element scales.

Watch the value hierarchy: on very small elements (icons under 24 pixels), even 8-pixel radii can look almost pill-shaped, while on very large hero cards a 4-pixel radius looks accidentally squared-off. Pair this tool with the hex to RGB converter for colors, the color mixer for blending accents, and the Open Graph meta generator when polishing a landing page.

People Also Ask

How do I make a rounded corner in CSS?

Add border-radius: 12px to your element. Larger numbers make rounder corners; use one value for all four corners or four different values for each corner independently.

What is the border-radius shorthand order?

Clockwise from the top-left: top-left, top-right, bottom-right, bottom-left. This tool always outputs all four values so the result is unambiguous.

How do I make a circle with CSS?

Apply border-radius: 50% to a square element (equal width and height). The percentage makes the shape a perfect circle at any size.

What is an elliptical border radius?

It gives a corner two values, a horizontal radius and a vertical radius, drawing an oval curve instead of a circular one. In CSS you write it with a slash: 40px 20px / 30px 15px.

Why do images spill over rounded corners?

The container's rounding does not clip its children in all browsers. Add overflow: hidden to the rounded container, or apply the same border-radius to the image directly.

Should I use pixels or percentages?

Pixels for fixed-size elements like buttons and cards, and percentages (especially 50%) for anything that must scale, like avatars. Pill shapes use 999px so the browser rounds to the element's height.

Can I use border-radius on buttons?

Yes. Buttons are the most common use. 8 to 12 pixels reads as modern and professional; 999 pixels turns the button into a pill.

Does border-radius work on images and videos?

Yes. It works on any element that renders a box, including img, video, and iframe. Add overflow: hidden to the wrapper if a child element still shows sharp corners.