How to Calculate Device Pixel Ratio
What is Device Pixel Ratio?
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.
Formula
- DPR
- Device Pixel Ratio (Ratio)
- PPI
- Pixels per inch (Density)
Step-by-Step Guide
- 1DPR = Physical pixel resolution / CSS (logical) resolution
- 2At DPR 2: serve 2x resolution images for sharp display on Retina screens
- 3The srcset HTML attribute lets browsers automatically choose the appropriate resolution
Worked Examples
Frequently Asked Questions
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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