Screen Resolution Test
See your display's native resolution in physical pixels, along with its pixel ratio, aspect ratio and color depth. Then launch a fullscreen 1-pixel test pattern: at true native resolution it reads as a clean, even texture, while scaling or a non-native mode shows up as blur or moiré.
Detecting…
← → switch pattern
Alternating pixels blend to a smooth grey — the display is running at native resolution and 100% scaling.
The image is being stretched — the resolution is likely set below native, so the GPU is upscaling.
Rippling patterns come from interpolation. Reset browser zoom to 100% and check for OS display scaling.
Screen resolution is how many pixels a display shows, written as width × height — 1920 × 1080, for example. More pixels over the same area means a sharper, denser image. Every flat panel has one fixed grid of physical pixels it is built to show, called its native resolution, and it looks sharpest running at that resolution. This test reads the physical pixel grid your browser reports and shows it as the big number above, so you can confirm what your hardware is actually driving.
Pick a lower resolution and the GPU stretches a smaller image across the fixed grid, softening everything. Modern systems also add display scaling (Retina, Windows 150%) to draw the interface larger while still rendering at full density. That is why a browser reports two sizes: the CSS viewport in logical pixels and the physical resolution in real device pixels. The ratio between them is the device pixel ratio (DPR) — a DPR of 2 means each CSS pixel is backed by a 2 × 2 block of physical pixels, so the viewport your browser sees can be half the resolution of the screen.
Common screen resolutions
| Resolution | Name | Where you see it |
|---|---|---|
| 1280 × 720 | HD / 720p | Older laptops, entry-level displays |
| 1920 × 1080 | Full HD / 1080p | The most common desktop and laptop resolution |
| 2560 × 1440 | QHD / 1440p | Sharper gaming and work monitors |
| 3440 × 1440 | UltraWide QHD | 21:9 ultrawide panels |
| 3840 × 2160 | 4K UHD | Large and high-DPI screens, TVs |
| 1170 × 2532 | iPhone (DPR 3) | Modern phones — tall, high-density panels |
Tips for an accurate reading
- Reset browser zoom to 100% — zoom resamples the page independently of the OS.
- On Windows, pick the resolution marked “(Recommended)” under Settings > System > Display.
- On macOS, choose “Default for display” under System Settings > Displays.
- Run the fullscreen pattern: a clean, even grey means native output, while blur or moiré means scaling.