What is my device pixel ratio?
See your device pixel ratio (DPR), the link between CSS pixels and physical pixels on your screen. Detected live, nothing uploaded.
Your device pixel ratio is shown above. Often called DPR, it is how many physical screen pixels correspond to one CSS pixel, the unit web pages are laid out in. A standard display has a ratio of 1. High-density (Retina) displays report 2 or 3, packing more physical pixels into the same visual space for sharper text and images.
This is the number that reconciles two facts that seem to conflict: your phone has millions of physical pixels, yet CSS treats it as a few hundred pixels wide. The DPR is the multiplier. At a ratio of 2, a 400-pixel-wide CSS layout is drawn using 800 physical pixels, so everything looks crisp rather than tiny.
For anyone serving images, DPR is essential: it tells you whether to send a standard image or a higher-resolution version so it stays sharp on dense screens without wasting bandwidth on ordinary ones.
What you should know
Why sites collect it
Sites read DPR to serve the right image resolution (via srcset and similar), render sharp canvas and WebGL graphics, and lay out crisp interfaces on high-density screens. Getting it wrong makes images either blurry or needlessly heavy.
Privacy implications
DPR is a modest fingerprinting signal. Common values (1, 2, 3) are widely shared, but fractional ratios from OS display scaling (like 1.25 or 1.5) are more distinctive and, combined with resolution, help narrow your device.
How to change or hide it
Your DPR follows your display and your operating system scaling setting; changing the scaling changes the ratio and the size of everything on screen. Privacy browsers may report a rounded value to reduce distinctiveness.
Frequently asked questions
What does a device pixel ratio of 2 mean?
Two physical pixels are used for each CSS pixel, so the display is high-density and needs higher-resolution images to look sharp. Retina screens typically report 2 or 3.
Why is my DPR a fractional number like 1.5?
Operating system display scaling can produce fractional ratios. Setting your scale to 150 percent, for instance, yields a DPR of 1.5.