Why is my physical resolution higher than the reported resolution?

High-DPI (Retina) screens use a device pixel ratio above 1, so the physical pixel count is the CSS resolution multiplied by that ratio. A 2560×1440 screen at 2× reports 5120×2880 physical pixels.

Is the screen resolution different from the browser viewport?

Yes — screen resolution is the whole display, while the viewport is just the area inside the browser window after toolbars and scrollbars. Both are shown here.

Is any of this sent to a server?

No — all values come from your own browser via the standard screen API and stay on your device.

Screen Resolution Checker

See your screen resolution, pixel ratio and aspect ratio live.

Screen resolution checker

Instantly see your screen resolution, the physical pixel count after the device pixel ratio, the available area excluding the taskbar, your browser viewport, aspect ratio and colour depth.

Everything is read directly from your browser and updates as you resize the window — nothing is uploaded.