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Browser Dimensions

View your browser viewport, window, and screen dimensions in real time. Perfect for responsive design, breakpoint testing, and CSS media queries. Updates automatically as you resize the window.

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JavaScript is required. This tool runs entirely in your browser.

Table of Contents

What are Browser Dimensions?

Browser dimensions are the pixel measurements of your browser window and display. This tool shows the viewport (the area where web content is visible), the window (including browser chrome), and the screen (your display). It updates in real time as you resize the window.

All values are read from your browser's JavaScript APIs. No data is sent to any server.

Viewport vs Window vs Screen

  • Viewport (inner): The visible area for web content — excludes address bar, toolbars, and scrollbars. Use this for responsive design and 100vw / 100vh behavior.
  • Window (outer): The full browser window including chrome. Useful when testing window sizing or fullscreen behavior.
  • Screen: Your physical display resolution. screen.availWidth and screen.availHeight exclude taskbars and OS UI.

Common Use Cases

  • Responsive design: Verify breakpoints and media query behavior at different viewport sizes.
  • CSS debugging: Check actual viewport dimensions when 100vw or 100vh behave unexpectedly.
  • Documentation: Capture viewport sizes for design specs or testing guides.
  • Device testing: Compare dimensions across different devices and zoom levels.

Frequently Asked Questions

Why does viewport differ from window?

The viewport excludes the browser's UI (address bar, tabs, bookmarks bar, scrollbars). The window includes everything. On mobile, the address bar often hides on scroll, so the viewport can change.

What is device pixel ratio?

Device pixel ratio (DPR) is the ratio of physical pixels to CSS pixels. On a Retina or high-DPI display, DPR might be 2 or 3 — one CSS pixel maps to multiple physical pixels. This affects image sharpness and the rendering of 1px borders.

Is my data sent anywhere?

No. All dimension values are read locally in your browser. Nothing is uploaded or stored.