ZeroServer.tools

Browser Window Size Checker

Live-view your current browser window size, screen resolution, and device pixel ratio.

Window Size

0 × 0

window.innerWidth × innerHeight (CSS px)

Screen Resolution

0 × 0

window.screen.width × height

Device Pixel Ratio

window.devicePixelRatio

Physical Pixels

0 × 0

Window size × DPR

Responsive Breakpoint

Mobile (<640px)

Common CSS framework breakpoint bucket

Window Width vs. Full Screen Width

Your window currently uses 0% of your screen's width.

Resize your browser window to see the values update in real time.

How the Browser Window Size Checker works

This tool reads window.innerWidth and window.innerHeightto show your browser window's viewport size in CSS pixels, and window.screen.width / heightfor your monitor's full screen resolution. The Device Pixel Ratio (window.devicePixelRatio) tells you how many physical screen pixels map to a single CSS pixel — on a standard display it is 1x, while Retina/HiDPI displays are typically 2x or 3x. Multiplying window size by DPR gives the physical pixel dimensions actually being rendered by the display hardware. All values update live as you resize the window, so it's useful for checking how a layout behaves at specific breakpoints or for confirming exact dimensions before taking a screenshot.

Private & free — this tool runs entirely in your browser.