🎨 CSS Unit Converter & Calculator

Convert between CSS units: px, em, rem, vh, vw, %, pt, pc, in, cm, mm. Professional tool for responsive web design and development.

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🔄 CSS Unit Converter

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📊 All Unit Conversions

🧮 Advanced CSS Calculator

📖 CSS Unit Reference

Unit Type Description Use Case Browser Support
px Absolute Pixels - fixed size units Precise layouts, borders, shadows ✅ Universal
em Relative Relative to parent element font size Scalable components, margins ✅ Universal
rem Relative Relative to root element font size Consistent scaling, typography ✅ IE9+
vh Viewport 1% of viewport height Full screen sections, mobile layouts ✅ IE9+
vw Viewport 1% of viewport width Responsive typography, containers ✅ IE9+
vmin Viewport 1% of smaller viewport dimension Square elements, mobile-first ✅ IE9+
vmax Viewport 1% of larger viewport dimension Background sizing, overlays ✅ IE9+
% Relative Percentage of parent element Flexible layouts, responsive design ✅ Universal
pt Absolute Points (1/72 of an inch) Print stylesheets ✅ Universal
ch Relative Width of the "0" character Monospace layouts, code blocks ✅ IE9+

💡 Practical Examples

🎨 Typography Scaling

/* Base font size */ html { font-size: 16px; } /* Scalable typography */ h1 { font-size: 2.5rem; } /* 40px */ h2 { font-size: 2rem; } /* 32px */ h3 { font-size: 1.5rem; } /* 24px */ p { font-size: 1rem; } /* 16px */ small { font-size: 0.875rem; } /* 14px */

📱 Responsive Containers

/* Full viewport sections */ .hero { height: 100vh; } /* Responsive width */ .container { width: 90vw; max-width: 1200px; } /* Flexible grid */ .grid-item { width: calc(25% - 1rem); }

🔧 Component Spacing

/* Component with em-based spacing */ .card { padding: 1.5em; margin-bottom: 1em; border-radius: 0.5em; } /* Scales with font size */ .large-card { font-size: 1.2em; }

🎯 Precise Layouts

/* Pixel-perfect borders */ .button { border: 1px solid #ccc; box-shadow: 0 2px 4px rgba(0,0,0,0.1); } /* Fixed sidebar */ .sidebar { width: 250px; }

📐 Flexible Grid System

/* CSS Grid with mixed units */ .grid { display: grid; grid-template-columns: 250px 1fr 20%; gap: 2rem; } /* Flexible areas */ .content { grid-column: 2; }

🎬 Animation & Transitions

/* Viewport-based animations */ @keyframes slideIn { from { transform: translateX(-100vw); } to { transform: translateX(0); } } /* Scalable hover effects */ .card:hover { transform: scale(1.05); box-shadow: 0 1rem 2rem rgba(0,0,0,0.2); }

📚 CSS Units Best Practices

🎯 When to Use Each Unit

  • px: Borders, shadows, precise layouts, small details
  • rem: Font sizes, consistent spacing, layout components
  • em: Component-specific spacing, scalable elements
  • vh/vw: Full-screen sections, responsive typography
  • %: Flexible layouts, responsive containers
  • ch: Code blocks, monospace layouts

📱 Responsive Design Strategy

  • Use rem for typography to maintain scale relationships
  • Use em for component spacing that should scale with text
  • Use vh/vw for full-viewport elements
  • Use % for flexible container widths
  • Use px for fixed elements like borders and shadows

⚡ Performance Considerations

  • Avoid excessive use of viewport units in animations
  • Use rem over em when possible for better performance
  • Be cautious with vmax and vmin on older devices
  • Consider calc() for complex responsive calculations

🎨 Design System Integration

  • Establish a consistent rem scale for typography
  • Define spacing units using rem multiples
  • Use CSS custom properties for scalable design tokens
  • Create utility classes for common unit patterns

🔍 Accessibility Guidelines

  • Always use relative units for font sizes
  • Ensure touch targets are at least 44px (iOS) or 48px (Android)
  • Test with browser zoom up to 200%
  • Provide sufficient color contrast at all sizes

🛠️ Development Tips

  • Use browser dev tools to inspect computed values
  • Test responsive units across different screen sizes
  • Consider using CSS-in-JS for dynamic unit calculations
  • Document your unit choices in style guides