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Screen Resolution

The Screen Resolution Checker instantly displays your current screen resolution, device pixel ratio, viewport size, and color depth. Developers and designers use this tool to understand exactly what display environment their users are working in — essential for responsive design testing, media query breakpoints, and understanding how your site renders across different devices.

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About the Screen Resolution Checker

The Screen Resolution Checker instantly displays your current screen resolution, device pixel ratio, viewport size, and color depth. Developers and designers use this tool to understand exactly what display environment their users are working in — essential for responsive design testing, media query breakpoints, and understanding how your site renders across different devices.

How to use it

  1. Open the tool — screen data is detected automatically from your browser.
  2. View screen resolution, viewport size, and device pixel ratio.
  3. Check color depth, orientation, and browser window dimensions.
  4. Resize your browser window to see viewport dimensions update in real time.

Formula & methodology

Screen resolution: screen.width x screen.height (physical pixels). Viewport: window.innerWidth x window.innerHeight (CSS pixels). Device pixel ratio (DPR): window.devicePixelRatio. Physical pixels = CSS pixels * DPR. A 1440x900 screen at 2x DPR reports as 2880x1800 physical but 1440x900 CSS. Color depth: screen.colorDepth (typically 24-bit = 16.7M colors).

Common use cases

  • Checking your viewport size during responsive design development
  • Verifying device pixel ratio for HiDPI/Retina display optimization
  • Testing media query breakpoints across different screen sizes
  • Documenting screen specs when reporting display-related bugs
  • Confirming resolution before capturing screenshots for documentation

Frequently asked questions

Device pixel ratio (DPR) is how many physical screen pixels correspond to one CSS pixel. On a Retina/HiDPI display, DPR is typically 2 or 3 — meaning a 1px CSS element renders as 2x2 or 3x3 physical pixels for sharper display. This matters for images: if you use a 100x100px image on a 2x DPR screen, supply a 200x200px image to avoid blur.
As of recent data, 1920x1080 (Full HD) is the most common desktop resolution globally at around 20-25% of users. Mobile is dominated by 360x640 to 414x896 CSS pixel viewports (physical pixels vary by DPR). For web development, design for minimum 320px width (small phones) up to 1920px+ for large monitors, with key breakpoints at 768px (tablet) and 1024px (desktop).

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