Your viewport size

Refresh rate estimates browser frame callbacks, not the panel’s hardware rate. Keep this tab visible; power saving and other work can affect the result.

Inspect colors for stuck or dark pixels, gradients for abrupt transitions, and the checkerboard for contrast. Use fullscreen or the test area on this page.

Visual viewport

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Document client area

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The viewport is the page area inside the current browser window. The main reading is the layout viewport: window.innerWidth × innerHeight in CSS pixels, the units used to lay out web pages. Resize or rotate the window to see it change. The screen size above is also measured in CSS pixels and the pixel ratio can be affected by browser zoom or display scaling; neither identifies the panel’s native resolution.

With classic scrollbars the browser reserves part of that width, so the document client area is the space left for the page. The visual viewport is the part you can see right now; it changes with pinch zoom or an on-screen keyboard and is not reported by every browser.