CSS Glassmorphism Generator
Generate CSS glassmorphism effects with backdrop blur, transparency, and border controls. Live preview over a colorful background.
About CSS Glassmorphism Generator
Glassmorphism is a UI design style where elements look like frosted glass - semi-transparent with a blur effect that lets background content show through. The effect is built from a few CSS properties: backdrop-filter for blur, an rgba background for transparency, a subtle border for edge definition, and border-radius for rounding. This generator gives you sliders for each property with a live preview.
The CSS Properties Behind Glassmorphism
| Property | Role | Typical Value |
|---|---|---|
| backdrop-filter: blur() | Blurs everything behind the element | blur(12px) to blur(20px) |
| -webkit-backdrop-filter | Safari compatibility prefix | Same as above |
| background | Semi-transparent tint over the blur | rgba(255,255,255,0.15) to rgba(255,255,255,0.25) |
| border | Subtle edge definition | 1px solid rgba(255,255,255,0.2) |
| border-radius | Rounded corners for the glass panel | 12px to 20px |
| box-shadow | Optional depth effect | 0 8px 32px rgba(0,0,0,0.1) |
Example output:
background: rgba(255, 255, 255, 0.18);
backdrop-filter: blur(16px);
-webkit-backdrop-filter: blur(16px);
border: 1px solid rgba(255, 255, 255, 0.25);
border-radius: 16px;
How to Get a Good Glass Effect
| Parameter | Low | Medium (recommended) | High |
|---|---|---|---|
| Blur | 4-8px (barely frosted) | 12-20px (natural glass) | 30-50px (completely opaque blur) |
| Background opacity | 5-10% (nearly transparent) | 15-25% (frosted tint) | 40-60% (more solid than glass) |
| Border opacity | 10-15% (barely visible) | 20-30% (subtle definition) | 40-50% (strong edge) |
The sweet spot for most designs is blur 12-20px with background opacity 15-25%. Lower values look barely there; higher values start to look more like a solid panel than glass. The effect only works when there is colourful or varied content behind the element - a plain white background will not show the frosting.
Glass Colour Variations
| Tint | Background Value | Best Over |
|---|---|---|
| White frost (classic) | rgba(255,255,255,0.18) | Dark or colourful backgrounds |
| Dark glass | rgba(0,0,0,0.3) | Light or colourful backgrounds |
| Blue tint | rgba(59,130,246,0.15) | Dark backgrounds for a cool tech feel |
| Warm glow | rgba(251,146,60,0.12) | Dark backgrounds for a warm feel |
| Brand colour | rgba(your-brand-rgb, 0.15) | Any background matching your brand |
Where Glassmorphism Works Well
| UI Element | Why Glass Works |
|---|---|
| Navigation bars | Lets hero content show through while maintaining readability |
| Cards over images | Content overlays that do not completely obscure the background |
| Modals and dialogs | Maintains context of the page behind while focusing attention |
| Sidebar panels | Lighter visual weight than opaque sidebars |
| Pricing tables | Highlighted tier with glass stands out from opaque neighbours |
| Notification toasts | Non-intrusive overlays that blend with the page |
Accessibility Considerations
Glassmorphism can reduce text readability if the background behind the glass is too busy or the contrast is too low. Best practices:
- Test text contrast against both the glass tint and the content behind it - use the Color Contrast Checker
- Use darker text on light glass and lighter text on dark glass
- Increase the background opacity if text is hard to read
- Add a fallback for users who have "reduce transparency" enabled in their OS (use the prefers-reduced-transparency media query)
Performance Notes
backdrop-filter is GPU-accelerated in modern browsers, but heavy blur on many overlapping elements can affect performance on low-end devices. Tips:
- Use glassmorphism selectively - on a few key elements, not every surface
- Keep blur values reasonable (under 30px for most cases)
- Avoid stacking multiple backdrop-filtered elements on top of each other
- Test on mobile devices where GPU power is more limited
Browser Support
backdrop-filter is supported in Chrome 76+, Firefox 103+, Safari 9+ (with -webkit- prefix), and Edge 17+. The -webkit-backdrop-filter prefix is still needed for Safari compatibility. The tool includes both prefixed and unprefixed properties in its output.
For gradient backgrounds behind your glass, the CSS Gradient Generator creates colourful backgrounds that make the glass effect pop. For adding depth, the CSS Box Shadow Generator creates layered shadows.
All processing is local. Nothing leaves your browser.
Frequently Asked Questions
What CSS properties does glassmorphism use?
Glassmorphism relies on backdrop-filter for the blur effect, a semi-transparent background color using rgba, a subtle border for definition, and border-radius for rounded corners. The tool generates all of these properties plus the -webkit- prefix for Safari compatibility.
Does backdrop-filter work in all browsers?
Yes, backdrop-filter is supported in all modern browsers including Chrome, Firefox, Safari, and Edge. The tool includes the -webkit-backdrop-filter prefix for older Safari versions. There is no support in Internet Explorer, but that browser is no longer maintained.
How do I get the best glass effect?
Start with a blur of 12-20px and a transparency around 15-25%. A subtle border opacity of 20-30% adds definition to the edge. The effect works best when there is colorful or varied content behind the glass element. Plain white backgrounds will not show the blur.
Can I use dark glass?
Yes. Switch the background color to black and adjust the transparency. The Dark Glass preset is a good starting point. Dark glass works well on light or colorful backgrounds and gives a tinted look to the content behind it.
Is this tool free and private?
Completely free with no login required. All CSS generation happens in your browser. Nothing is sent to any server.
Related Tools
Link to this tool
Copy this HTML to link to this tool from your website or blog.
<a href="https://toolboxkit.io/tools/css-glassmorphism-generator/" title="CSS Glassmorphism Generator - Free Online Tool">Try CSS Glassmorphism Generator on ToolboxKit.io</a>