Ask iGyaan : What is ppi (pixels per inch) ?

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Ask iGyaan : What is ppi (pixels per inch) ?

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We often get similar questions from multiple users, this new section is to address exactly that, and we begin with the most asked question in recent times.

User Question :

Bharat Addresses to “ppi” in his videos, what does this mean? and does it have any relation to the camera resolution?

iG Answer :

PPI (pixels per inch), often referred to as pixel density is a measurement of the resolution of display of the device in question. this can also be the density of the images captured by a camera, but in Bharat’s reference it is always in terms of the display of the device in question.

PPI, is an actual count of the number of pixels found in one inch of a display, which varies depending on the resolution of the display and the overall size of the display.

Lets clarify further:

             1. Calculate d_p.

d_p = \sqrt{w_p^2 + h_p^2}

2. Calculate PPI:

PPI = \frac{d_p}{d_i}


  • d_p is diagonal resolution in pixels,
  • w_p is width resolution in pixels,
  • h_p is height resolution in pixels and
  • d_i is diagonal size in inches.

The HTC One M9+ has a screen resolution of 1440×2560 px

So,  d_p =  [underoot of = (2073600 + 6553600)] =2937.2 (approx)

The diagonal size in inches is 5.2 inch, therefore d_p/d_i = 2937.2/5.2 =  564.84

Therefore the pixels per inch (ppi) of the HTC One M9+ = 565 (rounded)

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About The Author
Mobile phone lover, Deviana, is iGyaan's Mobile news correspondent
  • Samir Singh

    4 saal pehle se pata hai mujhe ppi

  • Raghavendra Nasare

    PPI OK. What are other factor influencing display quality?

  • Tanuj Kapoor

    oh thats amazing U0001f60d thanks iGyaan, but my maths is very weak U0001f62d

  • Sandeep Mishra

    Pythagoras theorem…simple

  • Shyam Kumar

    Very good research by deviana

  • Prateek Gupta


  • Harsh Kothari

    Prateek Randhawa pls read bro! :)

  • Ankur Bisht

    ppi pixels :P

  • AbhilashKumar

    what is the maximum resolution  a human eye can identify..??

  • Droider

    @Aarush Its clearly given in the post, anyways,
    if I have a ‘5’ inch phone with 1280*720 resolution, then, square and add both the no’s in resolution!
    [(1280)^2+(720)^2) = 2156800. Now take the square root of the number!
    square root of 2156800 = 1468.6048.
    Divide it by the screen size of the phone i.e. 5 inches!
    1468.6048/5 = 293.721 which is approx. 294 PPI.
    Ex: Canvas HD has 294 PPI. :)

  • Ashish Kumar

    Here’s a python script for python guys:
    import math as m
    x = int(raw_input(“Enter X pixels t”))
    y = int(raw_input(“Enter Y pixels t”))
    ss = float(raw_input(“Enter screen size in inches t”))
    ppi = m.sqrt(x*x + y*y)/ss
    print “Screen density = “,ppi,” ppi”

  • Gogoi Chao Chatradhar