Screen Resolution Checker — Screen, Viewport & DPR

How to use

1. Read the big CSS-pixel figure — that is what websites design against.
2. Check the effective resolution line for your panel's true pixel grid.
3. Resize the window (or rotate a phone) and watch the viewport rows update live.
4. Use the DPR row to explain why screenshots look bigger or smaller than expected.

About this tool

Screen-size questions get confusing fast: a “4K” laptop may report 1536 × 864 CSS pixels, a phone claims 390 points wide, and screenshots come out twice as large as expected. This checker separates the layers honestly. It shows your display size in CSS pixels, the available area after the taskbar or dock, the live viewport as you resize the window, color depth, orientation and — the number wallpaper sites actually want — the effective resolution in physical device pixels, computed as CSS size multiplied by devicePixelRatio. Everything updates live as you drag window edges or rotate a device, and the short note below the table teaches the CSS-versus-device pixel distinction in one read. The browser simply reports its own geometry; nothing leaves the page.

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