'What resolution is my screen?' has a surprisingly layered answer: the physical pixel count, the CSS viewport your browser actually exposes to websites, and the device pixel ratio (DPR) linking the two on high-density 'Retina' displays. Web developers, support technicians, and display shoppers all need these numbers — and they are buried in system settings.
This checker displays your screen resolution, current viewport size, device pixel ratio, and color depth live — resize the window and watch the viewport numbers follow.
How to Use This Tool
- Open the page — your screen and viewport metrics display immediately.
- Resize the browser window to see viewport values update live.
- Note the device pixel ratio to understand physical vs CSS pixels.
- Use the values when filing bug reports or testing responsive breakpoints.
Frequently Asked Questions
Why is the viewport smaller than my screen resolution?
The viewport is the area your browser gives to web pages — the screen minus the OS taskbar, browser chrome, and scrollbars, all measured in CSS pixels. On a high-DPR display, CSS pixels are also fewer than physical pixels by design.
What is device pixel ratio?
The number of physical pixels per CSS pixel. A DPR of 2 means a 100-pixel CSS square is drawn with 200×200 physical pixels — this is how 'Retina' screens render text so sharply, and why images need 2× versions to look crisp.
Which resolutions should I test my website against?
Check your own analytics first, but common 2026 baselines: 390×844 (typical phone), 768×1024 (tablet), 1366×768 and 1920×1080 (laptops/desktops). Responsive design makes exact numbers less critical than testing each breakpoint range.