What is the difference between window size and screen size?

window.innerWidth/Height is the size of the visible viewport inside the browser (excluding browser chrome). screen.width/height is the full physical display resolution of your device.

What are the breakpoint thresholds used?

The breakpoints follow Tailwind CSS defaults: xs < 640 px, sm 640–767 px, md 768–1023 px, lg 1024–1279 px, xl 1280–1535 px, 2xl ≥ 1536 px.

Why does devicePixelRatio matter?

devicePixelRatio tells you how many physical pixels map to one CSS pixel. A value of 2 means a Retina / HiDPI display. This affects image sharpness and SVG rendering.

Screen Size Checker

View window size, screen resolution, pixel ratio, and active breakpoint in real time.

Reading screen info...

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FAQ

What is the difference between window size and screen size?: window.innerWidth/Height is the size of the visible viewport inside the browser (excluding browser chrome). screen.width/height is the full physical display resolution of your device.
What are the breakpoint thresholds used?: The breakpoints follow Tailwind CSS defaults: xs < 640 px, sm 640–767 px, md 768–1023 px, lg 1024–1279 px, xl 1280–1535 px, 2xl ≥ 1536 px.
Why does devicePixelRatio matter?: devicePixelRatio tells you how many physical pixels map to one CSS pixel. A value of 2 means a Retina / HiDPI display. This affects image sharpness and SVG rendering.

The Screen Size Checker displays live browser viewport dimensions (window.innerWidth / innerHeight), physical screen resolution, device pixel ratio, and current orientation. It also shows which CSS breakpoint (xs, sm, md, lg, xl, 2xl) is currently active based on standard Tailwind-style width thresholds. Resize the window to see values update instantly.