Screen
Check screen resolution online
Monitor check in the browser: CSS pixels, DPR and viewport update when you resize the window.
What this screen check can do
- Live diagram screen → avail → window → viewport
- Physical pixels and Full HD / 2K / 4K label
- visualViewport size, offset and pinch-zoom scale
- Safe-area insets and CSS media (HDR, P3, dark)
- PPI calibration from physical pixels and device preset overlays
- Fullscreen and JSON export
How to check your screen online
Open the tool
Metrics are read immediately — no installation.
Watch the diagram
Resize the window: screen and viewport layers update live.
Tune PPI
Enter your monitor diagonal in inches to get pixel density.
Compare a preset
Overlay iPhone / FHD / 2K / 4K on top of the current viewport.
Frequently asked questions
How do CSS pixels differ from physical ones?
CSS pixels are logical. Physical = CSS × DPR. On Retina, 1920 CSS can mean 3840 physical pixels.
Why visualViewport?
On mobile pinch-zoom, layout viewport and what you see diverge — visualViewport reports the visible area.
Why does my 4K screen report less than 3840×2160?
OS scaling changes CSS pixels: at 150% scaling a 3840×2160 panel reports 2560×1440 logical pixels — the tool shows both values and the DPR.
What is color depth?
Bits per pixel used to represent color: 24-bit gives 16.7M colors, while 30-bit panels support HDR with smoother gradients.