Reads your browser-reported screen size in CSS pixels, available area, and estimated physical pixel grid — all live as you resize.
Your browser-reported screen size is
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Screen resolution is the number of pixels your display shows, written as width × height. More pixels mean more detail at the same physical size. Two displays with the same resolution can look very different in sharpness if their physical sizes differ — that difference is measured inPPI (pixels per inch).
The value your browser reports is expressed in CSS pixels and may be affected by operating-system scaling. Multiplying it by your device pixel ratioprovides an estimated physical pixel grid, not a guaranteed native panel resolution. For a reference list of typical values, see common screen resolutions. If the browser, operating system and manufacturer all show different numbers, follow thedisplay scaling guide to separate native resolution, logical workspace, DPR, viewport size and browser zoom.
The total screen size describes the display. The available screen subtracts operating-system areas such as a taskbar or dock. That distinction matters for kiosks, multi-monitor setups and screenshots, but it is not the same thing as the CSS viewport.
Use the native resolution from your operating system or manufacturer when documenting hardware. Use the browser-reported screen size for environment reports, viewport size for web layout bugs and DPR for high-density image questions.
The result above is the screen size reported to your browser in CSS pixels. To confirm the display's native resolution, check Settings → System → Display on Windows, System Settings → Displays on macOS, or the device manufacturer's specifications.
It means your display is 1920 pixels wide and 1080 pixels tall — about 2.07 million pixels in total. This resolution is also called Full HD or 1080p and has a 16:9 aspect ratio.
Your operating system may apply scaling on high-density displays, so browsers often report a smaller size in CSS pixels. Multiplying that value by DPR gives an estimated physical pixel grid, but browser zoom, display scaling and multi-monitor behavior mean the estimate may not match the native panel resolution.
Indirectly. Websites respond to the browser viewport, not the screen. A 4K monitor with a half-size browser window renders the same layout as a smaller screen. See the viewport size checker for the value that actually drives responsive design.