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Border Radius Previewer

Visualize and generate CSS border-radius values

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What is Border Radius Previewer?

Border Radius Previewer is a free online tool that helps you visualize and generate css border-radius values. It runs entirely in your browser using client-side JavaScript, so your data stays private and never leaves your device.

When to Use

  • Quickly previewing CSS effects, colors, or layouts during design
  • Generating design assets like gradients, shadows, or color palettes
  • Checking accessibility compliance for colors and visual elements

How to Use

Enter your input in the field above, adjust any settings if available, and click the action button. Results appear instantly—no page reload, no server wait. All processing happens locally in your browser.

Related Tools

Try our Box Shadow Generator for related functionality.

Deep Dive: How Border Radius Previewer Works

Border Radius Previewer bridges the gap between visual design and code implementation, helping designers and developers collaborate more effectively by providing instant visual feedback and code generation. The perennial challenge in web and UI development is translating visual design intent into precise CSS values—what looks right in a design tool may render differently across browsers, screen sizes, and color profiles. Border Radius Previewer provides interactive, real-time previews where you can experiment with visual properties and immediately see the result, then copy the exact production-ready CSS code. This tight feedback loop between visual manipulation and code output dramatically accelerates UI development workflows, reduces the iteration cycles of 'tweak value, rebuild, check' that slow down frontend work, and ensures consistency between design mockups and implemented interfaces.

Pro Tips

  • Copy the generated CSS exactly—manual tweaks often break cross-browser compatibility
  • Preview box shadows and border radius at different zoom levels to catch rendering artifacts
  • For gradients, include a solid fallback color for older browsers that don't support CSS gradients

Common Mistakes to Avoid

  • Using color alone to convey information—colorblind users won't perceive the difference
  • Not checking contrast ratios with actual content—tool previews may differ from real text

Frequently Asked Questions

How do I preview and generate CSS border-radius values?
Use a border radius previewer to visually adjust each corner's rounding with sliders. Apply uniform radius or customize each corner independently for asymmetrical shapes. The tool shows a live preview as you adjust values and outputs the CSS—'border-radius: 10px 20px 30px 40px;'—ready to copy into your project.
How does the CSS border-radius shorthand with 4 values work?
Four values follow the order: top-left, top-right, bottom-right, bottom-left (clockwise from top-left). Two values mean top-left/bottom-right and top-right/bottom-left. Three values mean top-left, top-right/bottom-left, bottom-right. A single value applies the same radius to all corners. The previewer helps visualize this shorthand.
Can I create circles and ellipses using CSS border-radius?
Yes, setting border-radius to 50% on a square element creates a perfect circle. On a rectangle, 50% creates an ellipse. For pill shapes (rounded rectangles), use a large fixed pixel value like border-radius: 9999px. The previewer lets you experiment visually with different shapes before writing any CSS.