What Is My Screen Resolution — Detect Display Size

Your screen resolution

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How to use What Is My Screen Resolution

Open the page — your dimensions appear automatically.
Read screen resolution, window size and pixel ratio.
Use the viewport size for responsive design — that's what your layout responds to, not the screen.
Check pixel ratio for image sharpness on high-DPI displays.

What is What Is My Screen Resolution?

This tool displays your screen resolution and related dimensions — your full display resolution (e.g. 1920×1080), your current browser window size (which is usually smaller), and your device pixel ratio (how many physical pixels map to each CSS pixel, relevant for high-DPI "Retina" displays). It answers "what's my screen resolution?" and the window/pixel details that design and support work often need.

These numbers matter more than they seem: web design responds to them, support diagnoses layout issues with them, and the distinction between screen size, window size and pixel ratio trips up even developers.

About the What Is My Screen Resolution

Open the page and read your screen and window dimensions instantly.

What it shows and why: screen resolution — your monitor/display's full pixel dimensions; browser window (viewport) size — the actual space your web content has, which is smaller than the screen (toolbars, taskbars, non-maximized windows) and is what responsive design actually responds to; and device pixel ratio — on high-DPI displays (Retina, modern phones), each CSS pixel is 2 or 3 physical pixels, which is why images need to be higher-resolution than their display size to look sharp.

Who uses it: web designers and developers — testing responsive layouts, understanding the difference between screen and viewport (a common confusion — you design for the viewport, not the screen), and checking pixel ratio for image sharpness; support — diagnosing "the layout looks wrong" issues where resolution or zoom is the cause; and anyone curious about their display specs. The privacy angle: like browser and user agent, your screen resolution is visible to every website automatically and contributes to fingerprinting. Related tools: What Is My Browser, What Is My User Agent, and our Screen Resolution Simulator (for testing how a site looks at other resolutions).

Frequently Asked Questions

Screen resolution is your display's full pixel dimensions; window (viewport) size is the actual space your web content has — smaller, because of toolbars, taskbars and non-maximized windows. Responsive design responds to the VIEWPORT, not the screen.

How many physical pixels map to each CSS pixel — 1 on standard displays, 2-3 on high-DPI (Retina, modern phones). It's why images need to be 2× their display size to look sharp on Retina screens; a 400px image displays crisply only if it's actually 800px on a 2× display.

Responsive design adapts layouts to the available space (viewport), so knowing real-world sizes helps you design for actual users. And pixel ratio determines image resolution needs. Designing for the viewport (not assumed screen sizes) is the responsive principle.

Because the browser window doesn't use the whole screen — the OS taskbar/dock, browser toolbars and address bar, and any non-maximized window all reduce the space content actually gets. The viewport is what's left for your web page.

Yes — automatically, like your browser and user agent. It's used for legitimately serving appropriate layouts, but also contributes to browser fingerprinting. It's one of the signals every site you visit can read about your device.