The big numbers above are your display's resolution as your browser reports it, along with the numbers developers and designers actually need: the browser viewport size, the device pixel ratio (how many physical pixels hide behind each CSS pixel), your aspect ratio and color depth. Resize the window and the values update live.
Note that on phones and high-DPI laptops the CSS resolution differs from the marketing resolution: a "4K" laptop typically reports 1920×1080 CSS pixels at a device pixel ratio of 2 — both numbers are shown here.
What people use it for
Web development
Check the real viewport and pixel ratio of any test device in one glance — the numbers CSS media queries actually see.
Support & remote help
Ask a user to open this page and read the numbers aloud: faster and more accurate than guiding them through system settings.
Display verification
Confirm a monitor is actually running at its native resolution — a surprisingly common cause of blurry screens after cable or driver changes.
Frequently asked questions
Why does my 4K screen show 1920×1080?
Your OS uses display scaling. The browser reports CSS pixels; multiply by the device pixel ratio shown here to get physical pixels — 1920×1080 at ratio 2 is exactly 3840×2160.
What is device pixel ratio?
The number of physical screen pixels per CSS pixel. Ratio 1 is a classic monitor, 2 is Retina/HiDPI, and phones commonly run 2.5–4.
What does the aspect ratio (e.g. 1.78) mean?
Aspect ratio is the width of your screen divided by its height. 1.78 is the decimal form of 16:9, the standard widescreen shape; 1.60 is 16:10, and ultrawide monitors show around 2.33 (21:9). It tells you the shape of the display, independent of how many pixels it has.
What is color depth (24-bit)?
Color depth is how many bits are used to describe the color of each pixel. 24-bit means 8 bits each for red, green and blue — about 16.7 million colors, the standard for almost every modern screen. 30-bit (10 bits per channel) is used by some HDR and professional displays for smoother gradients.
Why is my viewport smaller than my screen?
The viewport is only the area your browser has left for the web page, so it is almost always smaller than the full screen: the browser's tabs, address bar and bookmarks take space at the top, the operating system's taskbar or dock takes more, and the window itself may not be maximized. Maximize the window or press F11 for fullscreen and the viewport grows toward the CSS screen size.
Does this page send my data anywhere?
No — the values are read and displayed locally by your own browser. Nothing is transmitted or stored.