VH to PX Converter: Transform Viewport Height to Pixels

What is the difference between VH and VW?

VH (viewport height) is relative to the viewport's height, while VW (viewport width) is relative to the viewport's width. 1vh = 1% of viewport height, and 1vw = 1% of viewport width.

Example: On a 1920×1080px screen, 50vh = 540px (vertical) and 50vw = 960px (horizontal). Use VH for full-screen sections and vertical spacing, VW for responsive width sizing and horizontal layouts.

Why does 100vh not work correctly on mobile browsers?

Mobile browsers (Safari, Chrome Mobile) calculate 100vh including the space occupied by the address bar and navigation UI, but the actual visible viewport is smaller when these elements are displayed. This causes unwanted scrolling or cut-off content.

Solutions:

• Use 100dvh (dynamic viewport height) for modern browsers (Chrome 108+, Safari 15.4+)
• Use JavaScript to calculate true viewport height and set CSS custom properties
• Use min-height: 100vh instead of fixed height to allow content expansion

Should I use VH or percentage for element height?

The choice depends on what you want the height to be relative to:

• Use VH when you want height relative to the viewport (browser window), regardless of parent element size. Perfect for full-screen sections, hero banners, and modals.
• Use percentage (%) when you want height relative to the parent element's height. Better for nested components, cards, and container-based layouts.

Note: Percentage heights require the parent element to have an explicit height set, while VH works independently.

Can I use VH with Flexbox and CSS Grid?

Absolutely! VH units work seamlessly with modern CSS layout systems like Flexbox and Grid. This combination is powerful for creating responsive, full-screen layouts.

Common patterns:

• min-height: 100vh with Flexbox creates flexible full-screen layouts
• Grid with grid-template-rows: auto 1fr auto and height: 100vh for app shells
• VH for container heights, letting Flexbox/Grid handle content distribution

What are dvh, svh, and lvh units?

These are new viewport units (introduced 2022-2023) that provide better control over mobile viewport calculations:

• dvh (dynamic viewport height): Dynamically updates as browser UI shows/hides. Best for most mobile layouts.
• svh (small viewport height): Viewport height when all browser UI is visible. Ensures content never gets cut off.
• lvh (large viewport height): Viewport height when browser UI is hidden. Maximizes screen space.

Browser support: Chrome 108+, Safari 15.4+, Firefox 101+ (available since 2022).

How do I convert VH to pixels in JavaScript?

Use this simple formula to convert viewport height units to pixels dynamically:

function vhToPx(vh) {
  return (vh * window.innerHeight) / 100;
}

// Example usage
const fullScreen = vhToPx(100);  // Full viewport in pixels
const halfScreen = vhToPx(50);   // Half viewport
console.log(fullScreen);         // e.g., 1080

This is useful for scroll calculations, animations, and any JavaScript logic that needs viewport-aware measurements. Update on window resize events for responsive behavior.

Are there browser compatibility issues with VH units?

VH units have excellent browser support (98%+ globally) and work in all modern browsers:

• Chrome: Full support since version 20 (2012)
• Firefox: Full support since version 19 (2013)
• Safari: Full support since version 6 (2012) - mobile has address bar quirks
• Edge: Full support in all versions

The main issue is on mobile Safari where 100vh includes the address bar space. Use dvh units or JavaScript fixes for better mobile compatibility.