Free CSS Border Radius Generator Online

What the CSS Border Radius Generator Does

Getting rounded corners right in CSS should not require guesswork. The border-radius property accepts up to four values and three different unit types, which means there are hundreds of possible combinations for any given element. Typing values into your code editor, saving, and switching to a browser to check the result is slow and tedious, especially when you are fine-tuning asymmetric shapes.

This CSS Border Radius Generator gives you a visual interface for shaping corners in real time. Drag sliders, watch the preview update instantly, and copy the finished CSS or Tailwind class directly into your project. It is built for front-end developers, UI designers, and anyone working with CSS who wants to move faster from concept to code. Everything runs 100% client-side in your browser — no data is sent to any server, no signup is required, and there is nothing to install.

How It Works

The tool opens with a two-column layout: controls on the left, a live preview and code output on the right.

1. Choose a mode. Two toggle buttons at the top let you switch between Uniform and Per Corner mode. Uniform mode gives you a single slider that applies the same radius to all four corners. Per Corner mode expands into four independent sliders for Top Left, Top Right, Bottom Right, and Bottom Left, each displaying its current value in a monospace readout.

2. Pick your unit. Three unit toggle buttons — px, rem, and % — sit alongside the mode selector. Selecting a unit adjusts the slider range automatically: px goes up to 200, rem up to 10, and percent up to 50. The step size also adapts, incrementing by 0.25 for rem and by 1 for px and percent.

3. Adjust the sliders. Drag any slider and the preview element updates in real time. The preview area shows a bordered rectangle on either a dark or light background, toggled with the Light BG / Dark BG button above the preview. This lets you verify that your corner shape holds up against both themes without leaving the tool.

4. Try a preset. Below the sliders, a grid of 12 shape presets offers visual thumbnails you can click to load instantly: None, Subtle, Medium, Large, XL, Pill, Circle, Leaf, Ticket, Dialog, Drop, and Organic. Each preset sets the corner values, unit, and mode for you. From there, tweak any slider to customize.

5. Copy the output. Two output panels below the preview show the generated CSS and Tailwind CSS code. Each panel has a Copy button that places the code on your clipboard with a brief “Copied!” confirmation. The CSS output uses the most concise shorthand — a single value when all corners match, four values when they differ. The Tailwind output maps to built-in utility classes like rounded-lg or rounded-full when possible, and falls back to arbitrary-value syntax like rounded-[20px] or rounded-tl-[30px] for custom values.

Why Use Our CSS Border Radius Generator

Dual output saves a translation step. Most border-radius tools give you CSS only. This one generates both standard CSS and Tailwind utility classes side by side, so you never have to manually look up which rounded-* class maps to which pixel value.

Preset library with visual thumbnails. Instead of a dropdown list of names, each preset renders as a small shape so you can see what you are selecting before you click. Presets cover common patterns — pills for buttons, circles for avatars, leaf and drop shapes for decorative elements, dialog corners for chat UIs.

No account, no limits, no tracking. There is no login wall, no daily usage cap, and no analytics collecting your designs. The tool is a static page running JavaScript in your browser. Close the tab and nothing is stored anywhere.

Dark and light preview built in. Verifying border radius against both color schemes is one toggle away, not a separate workflow.

Use Cases

Card and container styling. Apply consistent corner rounding to cards, modals, and panels. Start with the Medium or Large preset and adjust to match your design system’s token values.

Button and tag shapes. Create pill-shaped buttons by loading the Pill preset, which sets all corners to 9999px — the standard CSS trick for a fully rounded edge regardless of element size. Fine-tune from there if you want a softer pill.

Avatar and profile images. Set the unit to percent and all corners to 50% using the Circle preset. This produces a perfect circle on any square element, which is the standard approach for circular avatar containers.

Decorative and asymmetric elements. Use Per Corner mode to create leaf shapes, teardrop accents, or organic asymmetric corners. The Leaf preset (0px top-left, 24px top-right, 0px bottom-right, 24px bottom-left) is a good starting point for diagonal accent shapes.

Chat and dialog UI. The Dialog preset rounds three corners uniformly while leaving the bottom-right corner subtle, mimicking the visual language of a speech bubble. Adjust the values to match your messaging interface.

Design system documentation. When defining border-radius tokens for a design system, use the tool to visualize each token value and copy the exact CSS for your documentation or token file.

Tips and Best Practices

Use rem for responsive designs. If your project scales with the user’s font-size preferences, rem-based radii will scale proportionally. A value of 0.5rem stays visually consistent whether the root font size is 16px or 20px.

Percent units behave differently on rectangles. Setting 50% on a square element produces a circle, but on a rectangle it creates an ellipse. If you want uniformly rounded corners on non-square elements, stick with px or rem.

Start from a preset, then customize. Rather than dragging sliders from zero, load the closest preset and make small adjustments. This is faster and often leads to more intentional corner values that align with common spacing scales.

Keep corner values consistent with your spacing scale. If your design system uses an 4-8-12-16 spacing scale, your border-radius values should follow the same progression. The Tailwind output panel makes this easy to verify — if you see built-in class names like rounded-lg instead of arbitrary values, your corners align with Tailwind’s default scale.

Test both light and dark themes. Rounded corners can look different against dark and light backgrounds, especially when borders are involved. Use the built-in background toggle to check both before committing your values.