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Glass Card

This is a live preview of your glassmorphism effect. Adjust the controls to see changes in real time.

Blur 12px

Transparency 0.15

Saturation 120%

Glass Tint

#ffffff

Border Radius 16px

Border Opacity 0.25

Shadow Blur 20px

Shadow Opacity 0.10

Preview Background

Generated CSS

Include @supports fallback

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About

Glassmorphism relies on the CSS backdrop-filter property combined with semi-transparent backgrounds to simulate frosted glass. The visual effect is a product of Gaussian blur radius (measured in px), background alpha channel (range 0 - 1), and subtle border luminance that mimics light refraction at glass edges. Incorrect values produce either an opaque block or an invisible layer. Browser support for backdrop-filter covers ~95% of global users, but Safari still requires the -webkit- prefix. This tool generates both prefixed and unprefixed declarations so your CSS works across engines without manual duplication.

The effect breaks down visually when placed over uniform backgrounds. Glassmorphism demands contrast variation behind the element. A blur radius below 4px reads as transparency rather than frosted glass. Above 40px, the blur obliterates background detail entirely, defeating the purpose. This generator clamps values to a practical range and renders a live preview over an animated gradient so you can evaluate the result under realistic conditions before copying the code.

Formulas

The glassmorphism effect is composed of four independent CSS declarations working together. The core blur function applies a Gaussian kernel of radius r to pixels behind the element:

backdrop-filter: blur(r) saturate(s%)

The background color uses RGBA notation where α controls the glass density:

background: rgba(R, G, B, α)

The border simulates light refraction at the glass edge. A white or light-tinted border with low opacity creates the characteristic rim-light:

border: 1px solid rgba(255, 255, 255, β)

The shadow provides depth separation from the background plane:

box-shadow: 0 y b rgba(0, 0, 0, γ)

Where r = blur radius in px, s = saturation percentage, α = background opacity (0 - 1), β = border opacity, y = shadow vertical offset, b = shadow blur spread, and γ = shadow opacity.

Reference Data

Property	Role in Glassmorphism	Recommended Range	Browser Support
backdrop-filter: blur()	Gaussian blur behind element	4 - 40px	Chrome 76+, FF 103+, Safari 9+ (-webkit-)
background (rgba)	Semi-transparent fill layer	Alpha 0.05 - 0.4	All browsers
border	Light-refraction edge simulation	1 - 2px, alpha 0.1 - 0.5	All browsers
border-radius	Rounded glass panel corners	8 - 32px	All browsers
box-shadow	Depth and elevation	Spread 0 - 40px, alpha 0.05 - 0.3	All browsers
-webkit-backdrop-filter	Safari prefix for blur	Same as backdrop-filter	Safari 9+
opacity	Global element transparency	0.8 - 1.0	All browsers
saturate()	Color vividness behind glass	100 - 200%	Chrome 76+, FF 103+, Safari 9+
brightness()	Lightens/darkens backdrop	80 - 120%	Chrome 76+, FF 103+, Safari 9+
Background contrast	Gradient or image behind glass	High variance required	N/A (design guideline)
Glass tint color	Hue of the frosted layer	White or brand color at low alpha	All browsers
Z-index stacking	Glass must overlay content	Context-dependent	All browsers
Text on glass	Contrast ratio compliance	WCAG AA: 4.5:1 minimum	Accessibility standard
Performance impact	backdrop-filter triggers compositing	Limit to 2 - 3 glass layers per viewport	GPU-dependent
Fallback strategy	Solid semi-transparent background	@supports query	All browsers

Frequently Asked Questions

Firefox did not support backdrop-filter until version 103 (July 2022). Older Firefox versions ignore it entirely. Safari requires the -webkit- prefix. This generator outputs both the standard and prefixed declarations. For unsupported browsers, wrap your glassmorphism styles in @supports (backdrop-filter: blur(1px)) and provide a solid rgba() fallback outside it.

An alpha between 0.10 and 0.25 on a white (255, 255, 255) background produces the clearest frosted glass illusion. Below 0.05, the layer becomes invisible. Above 0.40, it reads as a solid panel rather than glass. The optimal value depends on the blur radius: higher blur tolerates lower alpha because the blurred content provides visual density.

The backdrop-filter property forces the browser to composite a separate layer and apply a real-time Gaussian blur to everything behind it. Each glass element costs roughly 2-5ms of GPU time per frame depending on blur radius and element size. Stacking more than 3 glassmorphism layers in one viewport can cause frame drops on mobile GPUs. Avoid applying it to elements that animate position or size frequently.

Yes, but the tint color must shift. Instead of rgba(255, 255, 255, 0.15), use a dark tint like rgba(0, 0, 0, 0.25) and a lighter border. The blur effect itself is color-agnostic. The key requirement is contrast variation in the background content. A solid dark background with no gradient will not produce a visible glass effect regardless of settings.

Below 4px, the background content remains legible through the element, which reads as simple transparency rather than frosted glass. The perceptual threshold where users recognize the frosted effect is approximately 6-8px. Values above 30px obliterate all background detail, creating a soft color wash that loses the glass metaphor.

WCAG AA requires a contrast ratio of at least 4.5:1 for normal text. On a semi-transparent glass layer, the effective background luminance varies with the content behind it. Use a background alpha of at least 0.20, a blur radius of at least 10px, and test with both light and dark backgrounds. Adding a subtle text-shadow of 0 1px 2px rgba(0,0,0,0.1) on light glass improves legibility.