What is my pixel density?
Device pixel ratio (DPR) compares CSS pixels to physical device pixels. Values like 2 or 3 are common on high-density screens.
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Pixel density
Device pixel ratio (DPR)
DPR compares CSS pixels to physical device pixels. Values like 2 or 3 are common on high-density phone and laptop screens: one CSS pixel may map to multiple hardware pixels.
DPR is not the same as PPI (pixels per inch). PPI needs a true physical diagonal; DPR is what the browser exposes for layout and image sharpness.
Zoom and design impact
Browser zoom and OS scaling can change DPR. Sites use it to choose 2×/3× images so UI stays sharp. If sharp assets look soft, check zoom level and this DPR reading.
See screen size for an approximate inch estimate that combines resolution and ratio.
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Part of the display picture in screen resolution vs viewport.
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Frequently Asked Questions
What is device pixel ratio?
DPR is how many device pixels map to one CSS pixel. A DPR of 2 means a 1 CSS pixel square uses a 2×2 device pixel grid.
Is DPR the same as PPI?
No. PPI (pixels per inch) needs a physical diagonal. DPR is a browser scaling factor and does not equal PPI by itself.
Why do Retina screens show 2 or 3?
High-density displays pack more device pixels into the same CSS layout size, so the browser reports a higher ratio.
Does browser zoom change DPR?
Zoom can change effective layout sizes. The reported devicePixelRatio may stay the same depending on the browser.
Why do sites ask for DPR?
To serve sharper images (2x/3x assets) and avoid blurry UI on high-density screens.