Viewport Size Tester
Check your browser's real-time viewport size, screen resolution, device pixel ratio, and orientation.
Active Mode: Live WindowViewport: 0 × 0 pxAspect Ratio: -DPR: 1xBreakpoint: Mobile (<640px)
Visual Proportion Preview (-)0 × 0 px
0 × 0Mobile (<640px)
Viewport (CSS px)
0 × 0
window.innerWidth × innerHeight
Screen Resolution
0 × 0
Total physical screen pixels
Available Screen
0 × 0
Minus taskbar / OS UI
Device Pixel Ratio
1x
window.devicePixelRatio
Physical Pixels
0 × 0
CSS px × DPR
Orientation & Aspect
unknown
Ratio: -
Resize your browser window to see live values update in real time. Select preset dimensions to quickly test responsive breakpoint criteria.
What is viewport size & responsive breakpoints?
The viewport is the visible area of a web page expressed in CSS pixels. window.innerWidth and innerHeight give the live viewport dimensions excluding browser chrome. The Device Pixel Ratio (DPR) indicates how many physical device pixels render a single CSS pixel. Multiply viewport dimensions by DPR to obtain the exact physical resolution.
Private & free — this tool runs entirely in your browser.
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