PPI Calculator - How Is PPI Calculated

PPI Formula:

\[ PPI = \frac{\sqrt{PixelsWidth^2 + PixelsHeight^2}}{Inches} \]

Pixels Per Inch (PPI):

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1. What is PPI (Pixels Per Inch)?

Definition: PPI measures the pixel density of digital displays, indicating how many pixels fit into one linear inch of screen space.

Purpose: Higher PPI means sharper images and text, as more pixels are packed into the same physical space.

2. How Is PPI Calculated?

The calculator uses the formula:

\[ PPI = \frac{\sqrt{Width^2 + Height^2}}{Diagonal\ Size} \]

Where:

\( Width \) — Horizontal resolution in pixels
\( Height \) — Vertical resolution in pixels
\( Diagonal\ Size \) — Screen size measured diagonally in inches

Explanation: This formula calculates the diagonal pixel count (using Pythagorean theorem) divided by the physical screen size.

3. Importance of PPI

Details: PPI determines display sharpness. For example:

72-100 PPI: Typical for computer monitors
200-300 PPI: Smartphone screens
300+ PPI: High-end mobile devices

4. Using the Calculator

Tips: Enter your screen's resolution (width and height in pixels) and its diagonal size in inches. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Is PPI the same as DPI?
A: No, PPI refers to screen pixel density, while DPI (dots per inch) refers to printer resolution.

Q2: Does higher PPI always mean better quality?
A: Generally yes, but beyond ~300 PPI at normal viewing distances, the human eye can't perceive additional detail.

Q3: How do I find my screen's resolution?
A: On Windows: Display Settings. On Mac: About This Mac > Displays. Or check your device specifications.

Q4: What's the PPI of a 4K 27-inch monitor?
A: Approximately 163 PPI (3840×2160 resolution on 27" diagonal).

Q5: Why does my phone have higher PPI than my TV?
A: Phones are viewed closer, requiring higher PPI for the same perceived sharpness as larger screens viewed from farther away.