How to Calculate PPI

How to find Pixel Density (PPI) of a screen?

Pixels Per Inch (Pixel Density) Calculation

PPI (Pixels Per Inch) is the measurement of the pixel density (sharpness) of any display screen. It is used in the measurement of screen resolution of electronic devices like computer, mobile phones, television etc., Here is a simple step by step tutorial to measure the pixel density of the screen.
How To Calculate Ppi
Formula :
Pixels per inch (PPI) = dp / di
dp = √ w2p + h2p

Where,
dp= Diagonal resolution
wp = Width of the screen
hp = Height of the screen
di = Diagonal Size (in inches)
How To Calculate Ppi Formula
Example: Consider a 21.5 inch LCD TV with the screen resolution of 1024 x 768. Find the PPI of the LCD.
di = 21.5 inch
wp = 1024
hp = 768
Pixels Per Inch Calculation Step1
Step 2: Find dp (Diagonal resolution) of the LCD.
dp = √ w2p + h2p
= √(1024)2 + (768)2
= √ 1048576 + 589824
Pixel Density Calculation Step2
Step 3: Diagonal Resolution = √ 1638400
Pixles Per Inch Calculation Step3
Step 4: We got the Diagonal Resolution as 1280
Pixel Density Calculation Step4
Step 5: To find the pixels per inch of a LCD, substitute the obtained values in the formula.
PPI = dp / di
=1280/21.5
How To Calculate Ppi Step5
Step 6: Pixels Per Inch / Pixel Density = 59.5
How To Calculate Ppi Step6


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