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如何计算Device Pixel Ratio

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Device Pixel Ratio (DPR) is the ratio between physical pixels and logical CSS pixels. On Retina displays, one CSS pixel maps to 4 or 9 physical pixels, requiring higher-resolution images.

公式

DPR = Physical pixel resolution / CSS (logical) resolution
DPR
Device Pixel Ratio (Ratio)
PPI
Pixels per inch (Density)

分步指南

  1. 1DPR = Physical pixel resolution / CSS (logical) resolution
  2. 2At DPR 2: serve 2x resolution images for sharp display on Retina screens
  3. 3The srcset HTML attribute lets browsers automatically choose the appropriate resolution

例题解析

输入
iPhone 15 Pro: 2,556x1,179 physical, 393x852 CSS pixels
结果
DPR = 3x; 460 PPI - extremely sharp display

常见问题

What is Pixel Ratio Calc?

Device Pixel Ratio (DPR) is the ratio between physical pixels and logical CSS pixels. On Retina displays, one CSS pixel maps to 4 or 9 physical pixels, requiring higher-resolution images

How accurate is the Pixel Ratio Calc calculator?

The calculator uses the standard published formula for pixel ratio calc. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Pixel Ratio Calc calculator use?

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Pixel Ratio Calc calculator use?

The core formula is: DPR = Physical pixel resolution / CSS (logical) resolution. Each step in the calculation is shown so you can verify the result manually.

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