Screen resolution FAQ
Everything about screen resolutions, viewports, pixel ratios — and how this site measures them.
- Why is the resolution shown different from my monitor's advertised resolution?
- Browsers measure in CSS pixels, not physical pixels. On high-density (“Retina”) displays, one CSS pixel spans several physical pixels — that multiplier is the device pixel ratio. Multiply the reported resolution by the DPR to get your panel's native resolution. Browser zoom and OS display scaling also change the reported values.
- What's the difference between screen resolution and viewport size?
- Screen resolution covers your entire display. The viewport is just the part of the browser window a web page can use — it shrinks as toolbars, bookmarks bars, and dev tools take up space, and it changes whenever you resize the window.
- What is an aspect ratio?
- The proportion between a screen's width and height, reduced to its smallest whole numbers. Most monitors and TVs are 16:9, many laptops are 16:10 or 3:2, and ultrawide monitors are around 21:9. It's what determines whether videos and wallpapers fit your screen without black bars or cropping.
- Why do the numbers change when I zoom the page?
- Browser zoom resizes CSS pixels: zooming in makes each CSS pixel cover more physical pixels, so the device pixel ratio goes up and the reported resolution and viewport go down. Reset zoom with Cmd+0 (macOS) or Ctrl+0 (Windows) to see your display's unzoomed values.
- How do I change my screen resolution?
- On macOS, open System Settings → Displays and pick a scaled resolution. On Windows, open Settings → System → Display and use the display resolution dropdown. Flat-panel displays are sharpest at their native resolution, so lower settings trade crispness for larger UI.
- Does this site collect any of my data?
- Your measurements never leave your device — every number on this page is read locally by your browser using standard web APIs. To keep the site free we may show ads from third-party partners, which can use cookies where you've consented. See the privacy policy for details.