Border Radius Generator — CSS Border Radius Tool

Border Radius Generator — Visual CSS Corner Rounding Tool

The Serverless Tools Border Radius Generator is a free, browser-based visual editor for the CSS border-radius property. Instead of guessing pixel values and refreshing your browser, this tool provides intuitive sliders with live preview — making it effortless to create perfectly rounded corners, pill shapes, circles, blobs, and any custom corner configuration.

What Is CSS Border-Radius?

The CSS border-radius property defines the radius of an element's corners, creating rounded shapes from rectangular elements. The shorthand syntax border-radius: 10px rounds all four corners equally. For different corners, use border-radius: top-left top-right bottom-right bottom-left. Values can be in pixels (px) for absolute sizes or percentages (%) for relative rounding. Setting border-radius: 50% on a square element creates a perfect circle. The property supports elliptical corners using two values separated by a slash. Border-radius is part of CSS3 and is universally supported in all browsers.

Key Features

• Individual Corner Control — Separate sliders for top-left, top-right, bottom-right, and bottom-left corners.
• Linked Mode — Toggle to adjust all four corners simultaneously for uniform rounding.
• Pixel & Percentage Units — Switch between px and % to suit your design approach.
• Customizable Preview Box — Change width, height, background color, and border to match your design context.
• Live Preview — See the shape update instantly as you move any slider.
• One-Click CSS Copy — Copy clean, optimized CSS border-radius code to your clipboard.
• 100% Client-Side — No server processing needed.
• Shape Presets — Quick-apply common shapes: rounded rectangle, pill, circle, and more.

How It Works — Technical Overview

The Border Radius Generator manipulates CSS border-radius values using JavaScript event listeners on range inputs. Each slider corresponds to one corner and triggers an immediate CSS update on the preview element. The tool supports both the shorthand notation (when all corners are equal) and the full four-value notation (for asymmetric shapes). When units are switched between px and %, values are recalculated proportionally based on the preview element dimensions. The generated CSS output is optimized — using shorthand when possible.

Step-by-Step Guide

1. Open the Border Radius Generator — The tool loads with default rounded corners on a preview box.
2. Adjust Individual Corners — Use each corner's slider to set its border radius independently.
3. Or Use Linked Mode — Toggle the link button to adjust all corners together.
4. Switch Units — Toggle between px and % depending on your needs.
5. Customize the Preview — Change box dimensions and colors to visualize in your design context.
6. Try Shape Presets — Click preset buttons for common shapes like pills or circles.
7. Copy CSS — Click the copy button to get the border-radius CSS code.

Use Cases

• Web Designers — Create consistent corner rounding across buttons, cards, images, and containers.
• Frontend Developers — Generate exact CSS border-radius values without manual calculation.
• UI Component Libraries — Define standard border-radius tokens for design systems.
• CSS Art Creators — Create organic shapes for CSS art and geometric illustrations.

Tips & Best Practices

• Use design tokens — Define 3-4 standard border-radius values for your design system instead of ad-hoc values.
• Consider hover states — Slightly increasing border-radius on hover creates a subtle, satisfying interaction.
• Watch for overflow — Content inside highly rounded containers may be clipped. Use overflow: hidden if needed.
• 50% for circles — border-radius: 50% creates a perfect circle only on square elements.

Privacy & Security

All CSS generation happens locally in your browser. No data is transmitted to external servers. Your customizations and generated CSS code remain entirely on your device.

Browser Compatibility

border-radius CSS is universally supported across all modern browsers including Chrome, Firefox, Edge, Safari, and Opera. No vendor prefixes needed.