Reads every display property the browser exposes — screen width/height, viewport, device pixel ratio, color depth, color gamut, orientation, and more — and updates live as you resize the window.
Screen Resolution Test is a free, browser-based screen testing tool that runs the full check instantly in your web browser.
Modern browsers expose every relevant display property through the screen object and the window.devicePixelRatio property. This tool reads all of them and formats the results: CSS screen resolution, physical pixel resolution (CSS × DPR), browser viewport dimensions, device pixel ratio, color depth, advertised color gamut, orientation, aspect ratio, and available screen size. Everything runs in JavaScript on your machine — nothing is uploaded.
The big source of confusion: when your phone says "1080 × 2400" physical, the browser reports something smaller like "390 × 844" for screen.width / height. That's because CSS pixels are an abstraction chosen for consistent text size across devices. Multiply by devicePixelRatio (typically 2-3 on phones, 1-2 on desktops) to get the real pixel count. This tool does the multiplication for you.
The color-gamut CSS media query exposes which color gamut the OS and browser advertise. sRGB is the baseline — every display. DCI-P3 is wide-gamut, covering most modern phones, MacBooks, and premium monitors. Rec. 2020 is the UHD standard — rarely matched fully by consumer hardware. If you're doing color-critical work, this tells you whether the browser will render P3 images at full fidelity or remap to sRGB.
Windows DPI scaling (125%, 150%, 175%) reduces the reported CSS resolution — a 4K display at 150% scale reports as 2560 × 1440. macOS HiDPI similarly reports half-size logical resolutions. Browser zoom changes DPR at non-100% settings. Private or strict-privacy modes (Firefox, Brave) sometimes round values for anti-fingerprinting. If your numbers don't match the sticker on the monitor, check OS scale first.
Screen Resolution Test FAQ
