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Screen Resolution Checker

Read the screen, available area, viewport, outer window, device pixel ratio, and estimated backing-store pixel dimensions reported by this browser.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Open the page and compare CSS screen, available screen, viewport, and outer-window dimensions.
  2. 2.Review devicePixelRatio and the clearly labeled estimated device-pixel multiplication without treating it as physical size.
  3. 3.Resize or move the browser when comparing conditions, then select Copy report to save the visible browser values.

About Screen Resolution Checker

Screen Resolution Checker collects the display and window dimensions that this browser exposes and presents them with explicit labels. The report includes the full screen width and height in CSS pixels, available screen area, current viewport, outer browser window, device pixel ratio, estimated device-pixel dimensions, and portrait, landscape, or square orientation. Resize the browser to refresh viewport and outer-window values. Select Copy report to place the visible fields in plain text on the clipboard.

CSS screen dimensions come from screen.width and screen.height. They describe the coordinate space exposed to web content, not necessarily the panel's marketed or native resolution. Available screen dimensions come from screen.availWidth and screen.availHeight and may exclude operating-system interface areas such as a taskbar or menu region. Browser, operating system, privacy behavior, window mode, zoom, remote sessions, and multiple-display placement can affect what is exposed.

Viewport dimensions are window.innerWidth and window.innerHeight: the area available to the page's layout viewport, including any space defined by browser behavior. Outer window values are window.outerWidth and window.outerHeight when the browser provides positive values; the widget falls back to the viewport only when an outer value is unavailable. The difference between outer and inner dimensions can include browser chrome, borders, side panels, developer tools, and platform-specific decorations.

Estimated device pixels are calculated by multiplying the browser's CSS screen dimensions by devicePixelRatio and rounding to whole values. This is useful for understanding the relationship between CSS coordinates and a backing store, but the result is deliberately labeled an estimate. Display scaling, browser zoom, operating-system scaling, compositor behavior, screenshots, remote desktops, multiple panels, and privacy reduction can prevent that multiplication from matching a physical panel's native addressable pixels.

Orientation compares the reported CSS screen width and height. A greater width is Landscape, a greater height is Portrait, and equal values are Square. This label does not read an accelerometer, lock device orientation, or prove how a hinged, folded, rotated, mirrored, projected, or multi-monitor setup is physically arranged. It is only a classification of the two current reported numbers.

This tool cannot measure inches, centimeters, dots per inch, pixel pitch, color depth, refresh rate, HDR, gamut, brightness, panel type, physical diagonal, cable capability, GPU output mode, or EDID data. A normal web page does not receive enough trustworthy hardware information for those claims. Use operating-system display settings, manufacturer specifications, or dedicated hardware tools when purchasing, diagnosing, or calibrating a display.

For a useful troubleshooting report, copy the values before and after changing browser zoom, moving the window to another display, entering fullscreen, or changing operating-system scaling. Record the conditions outside this page because the widget intentionally saves no history. A change can show that the browser's coordinate environment changed; it does not by itself identify which layer caused the change.

All values are read locally from standard window and screen objects. No display identifier, report, clipboard content, or dimensions are uploaded or stored after reload. The contract is narrow: validate positive finite browser values, calculate an openly described multiplication, update on window resize, and distinguish CSS coordinates from estimated device pixels and from unobservable physical size.

Methodology & sources

Read positive finite values from screen.width/height, screen.availWidth/height, window.innerWidth/height, window.outerWidth/height, and devicePixelRatio. Estimate backing-store pixels as round(CSS screen × ratio), classify orientation by comparing reported CSS width and height, and refresh on window resize. Tests assert exact 1440×900 at ratio 2 → 2880×1800, all three orientations, report text, and invalid input rejection.

Frequently asked questions

Why is the viewport smaller than the screen?
The viewport is the page layout area inside the browser. Browser controls, window size, side panels, developer tools, and operating-system regions can make it smaller.
Are estimated device pixels the monitor's native resolution?
Not necessarily. Multiplying CSS dimensions by devicePixelRatio can differ from native panel pixels because of scaling, zoom, privacy reduction, compositing, or remote display behavior.
Can this measure physical screen size or DPI?
No. Browser dimensions do not provide a calibrated ruler, physical diagonal, pixel pitch, or trustworthy hardware DPI.

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