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Screen Resolution Checker — Display Size, Viewport, DPI & Pixel Ratio

Last verified May 2026 — runs in your browser

Screen Resolution Checker — Viewport, DPI, Pixel Ratio & Display Info

See exactly what your browser thinks your display is — physical screen width and height, the available area after subtracting taskbars and OS chrome, the inner viewport your CSS pixels actually fill, the device pixel ratio that determines whether `1px` in CSS becomes 1 or 2 or 3 hardware pixels, and the color depth your browser is rendering at. Every value updates live as you drag the window edge, which makes it useful for testing responsive breakpoints, verifying high-DPI behavior on a new monitor, or sanity-checking that your `transform: scale()` math accounts for devicePixelRatio.

Related: Color Picker Keyboard Tester Meta Tag Generator
About this tool

Values are pulled from `window.screen` (width, height, availWidth, availHeight, colorDepth, pixelDepth, orientation.type), `window.innerWidth/innerHeight` (the layout viewport in CSS pixels), and `window.devicePixelRatio` (the multiplier between CSS pixels and hardware pixels — 1 on classic displays, 2 on most Retina laptops, 3 on most flagship phones). The page subscribes to `resize` events so every metric refreshes the moment the browser changes dimensions, including device rotation and floating-window reflow on iPad and Android multi-window. The numbers reported are the same ones JavaScript code on any other site sees about your device, which is why ad-tech and fingerprinting libraries lean on them — knowing them helps you understand your own anti-fingerprinting setup. Common uses: picking a CSS breakpoint that matches a real user device, choosing a thumbnail size that doesn't blur on Retina, debugging a CSS scale transform on HiDPI, or confirming that a Chromebook reports the resolution you expect to your responsive image srcset.

  • Screen physical width × height (window.screen.width/height)
  • Available area after taskbar/OS chrome (availWidth/availHeight)
  • CSS layout viewport (window.innerWidth/innerHeight)
  • Device pixel ratio for Retina/HiDPI detection (1, 2, 3 typical)
  • Color depth + pixel depth in bits
  • Screen orientation type (portrait-primary, landscape-secondary, etc.)
  • Live updates on resize, rotation, and split-screen reflow
  • Effective hardware pixel count = viewport × devicePixelRatio
  • One-click copy of all metrics as a key-value dump
  • Useful for responsive CSS debugging, fingerprinting auditing, srcset sanity checks

Free. No signup. Your inputs stay in your browser. Ads via Google AdSense (consent required).