CSS Border Radius Generator

Rounded corners are one of those small design details that either look intentional or look like you dragged a slider randomly and went with whatever came out. The difference between a card that feels polished and one that feels slightly off is often a matter of a few pixels, applied inconsistently across corners. CSS border-radius is not a complicated property, but getting it right visually while writing values from memory is exactly the kind of task that benefits from immediate visual feedback.

This tool gives you that feedback. Adjust the values, watch the shape update in real time, copy the CSS when it looks right. No refreshing the browser, no switching between a code editor and a preview tab, no guessing at what border-radius: 40% 60% 70% 30% / 40% 50% 60% 50% actually looks like before you see it rendered.

How CSS Border Radius Actually Works

The border-radius property controls the curvature of an element's corners. At its simplest, a single value applies the same radius to all four corners uniformly. That covers most use cases: buttons, cards, badges, input fields. One value, four identical corners.

The property becomes more expressive when you start controlling corners individually. CSS allows you to set each corner separately using the longhand properties: border-top-left-radius, border-top-right-radius, border-bottom-right-radius, and border-bottom-left-radius. The shorthand follows a clockwise order from top-left when four values are specified.

The syntax also supports elliptical radii, where you define separate horizontal and vertical radii for each corner using a forward slash to separate the two sets of values. This is how you get pill shapes, egg shapes, leaf shapes, and various organic curves that go beyond simple circular rounding. The full syntax looks like this:

border-radius: [top-left] [top-right] [bottom-right] [bottom-left] / [top-left-vertical] [top-right-vertical] [bottom-right-vertical] [bottom-left-vertical];

Writing that from memory while simultaneously visualizing the result is not how design decisions get made well. The visual approach is considerably faster.

What the Tool Provides

The generator gives you individual control over each corner, either by entering values directly or by dragging visual controls to adjust the radius. The live preview updates as you change any value, so you see the exact shape you are creating before committing to it.

Preset shapes cover the most commonly needed patterns without requiring manual configuration. A perfect circle, a pill shape, rounded rectangle, and other standard forms are available as one-click starting points that you can then fine-tune if the exact proportions are not quite right.

Here is how to use it:

1. Use the controls to adjust corner radius values individually or together. Set all four corners uniformly for standard rounding, or break them apart for asymmetric shapes.
2. Watch the live preview update in real time as you adjust each value.
3. Switch to a preset shape if your target is a standard form, then adjust from there if needed.
4. Copy the generated CSS to your clipboard with one click, or download it as a file.

The output is standard CSS that works in every modern browser without vendor prefixes. The days of needing -webkit-border-radius and -moz-border-radius alongside the standard property are well behind us, but the tool generates clean, modern syntax regardless.

Practical Design Applications

Buttons. The most common use. Slightly rounded corners on a button feel friendlier than sharp right angles without going so far as a full pill shape, which reads differently depending on context. A radius of 4 to 8 pixels on a standard-height button is the range most UI systems land in. Full rounding to create a pill button works well for primary calls to action. Getting this consistent across a design system means picking a value and using it everywhere, which is much easier when you can preview it before deciding.

Cards and containers. A subtle radius on a card component, typically 8 to 16 pixels, lifts it visually from the background without making it look like a sticker. Larger radii, 24 pixels and above, create a softer, more informal feeling that works well in consumer-facing interfaces and less well in dense data displays.

Images. Applying border-radius to images is one of those things that looks good when done deliberately and looks accidental when done without thinking. A consistent radius applied uniformly to all images in a layout creates visual cohesion. Circles, created with border-radius: 50% on a square element, are standard for avatars and profile images.

Organic and decorative shapes. The elliptical radius syntax is where border-radius stops being utilitarian and becomes a design tool in its own right. Combining different horizontal and vertical radii across four corners produces shapes that would otherwise require SVG or image assets. Blob shapes, asymmetric curves, and leaf-like forms are all achievable in pure CSS. The visual editor makes these approachable because the relationship between the values and the resulting shape is genuinely not intuitive when writing it manually.

CSS Border Radius in Context

Border-radius is one piece of the CSS visual styling picture. For developers building components or page layouts, having quick access to the right generator for each CSS property saves the kind of cumulative time that is easy to underestimate.

If your workflow involves building gradient backgrounds alongside rounded shapes, the PNG Gradient Background Generator handles color stop and direction configuration with the same visual-first approach. For the broader code side of a front-end workflow, minifying your stylesheet before deployment is standard practice, and the CSS Minifier handles that without requiring any build tool configuration. If you are building and previewing HTML components that use your generated border-radius values, the Live Content Previewer lets you test HTML, CSS, and JavaScript together in real time without switching to a separate environment.

Browser Compatibility

The border-radius property has had full support across all major browsers since around 2012. There is nothing to polyfill, nothing to prefix, and nothing to test across modern browser versions. It works in Chrome, Firefox, Safari, Edge, and every mobile browser currently in meaningful use. The generated code from this tool requires no modification for cross-browser compatibility.

The one nuance worth noting is that overflow on child elements does not always respect the parent's border-radius in older implementations. If you are applying border-radius to a container and clipping child elements, adding overflow: hidden to the container resolves the most common edge cases. This is a CSS compositing behavior rather than a border-radius limitation, but it is the kind of thing that comes up often enough to be worth mentioning.

Frequently Asked Questions

What is the CSS border-radius property?

The border-radius CSS property rounds the corners of an element's outer border edge. It accepts one to four values to control each corner individually, and supports separate horizontal and vertical radii per corner for elliptical shapes. It applies to any block or inline-block element.

How do I make a perfect circle with CSS border-radius?

Apply border-radius: 50% to an element that has equal width and height. The percentage refers to the element's own dimensions, so 50% creates a radius equal to half the element's size, producing a circle.

What is the difference between border-radius and the individual corner properties?

border-radius is the shorthand property that sets all four corners in one declaration, in clockwise order from top-left. The longhand properties (border-top-left-radius, border-top-right-radius, border-bottom-right-radius, border-bottom-left-radius) set each corner individually and are useful when you need to override a single corner without rewriting all four values.

Do I need vendor prefixes for border-radius?

No. Vendor prefixes like -webkit-border-radius and -moz-border-radius were required in browsers from roughly 2009 to 2012 during the experimental implementation phase. All modern browsers support the standard border-radius property without prefixes.