数学

Pixel Density Calculator

PPI / Pixel Density Calculator

Width (px)

Height (px)

Screen diagonal (in)

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We're working on a comprehensive educational guide for the Pixel Density Calculator in your language. The content below is shown in English.

是什么 Pixel Density Calculator?

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A pixel density (PPI — pixels per inch) calculator determines screen sharpness from resolution and physical display size. Higher PPI = sharper image, less visible pixelation.

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公式

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f(x)PPI = √(width² + height²) / diagonal(inches); DPI ≈ PPI for screen density; higher = sharper

变量说明

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符号	名称	单位	描述
PPI	Pixels Per Inch	pixels/inch	—
d	Diagonal screen size	inches	—
w, h	Screen resolution	pixels	—

如何 Pixel Density Calculator

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1PPI = √(W² + H²) / diagonal (inches)
2W, H = horizontal and vertical resolution in pixels
3Apple Retina display threshold: ~300 PPI at arm's length
4TVs viewed from further away can be acceptable at 40–80 PPI

例题解析

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示例 1

已知:1920×1080 (Full HD) on 24" monitor

结果:PPI = √(1920²+1080²)/24 = √(3,686,400+1,166,400)/24 = √4,852,800/24 ≈ 91.8 PPI

实际应用

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Display quality assessment

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Retina/high-DPI display decisions

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Web design responsive breakpoints

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Image resolution requirements

PPI by Display Type

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Display	Typical PPI	Perceived sharpness
Budget phone	200–250	Acceptable
Mid-range phone	300–400	Sharp
iPhone (Retina)	460+	Very sharp
Budget monitor	72–100	Adequate at normal distance
4K 27" monitor	163	Very sharp for desktop

常见问题

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What's a good PPI?

Phone: 300+ PPI (retina). Laptop: 150-200 PPI. Desktop: 90-110 PPI. Higher = crisper text/images.

Why does screen size affect PPI?

Same resolution on larger screen spreads pixels farther apart = lower PPI. 1920×1080 at 24" vs 27" looks different.

How do I calculate if my screen is sharp enough?

Calculate PPI from resolution and diagonal. If >150 PPI, text is crisp. <90 PPI may show pixelation.

参考资料

›Pixel density — DisplayNinja

Mathematically verified

Reviewed October 2026

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