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There is much confusion in my organization around how many pixels are in a point and I have gone down a deep rabbit hole and I still do not have an answer to some questions which I am posting here...

First off, there are obvious differences between "physical pixels/device pixels" and CSS Pixels. As are there differences between "physical points" and point units on iOS.

This is a survey of what I have discovered:

on iOS What is pixel and points in iPhone?

  • 1 iOS point is equal to 1 physical pixel on a 1x device.
  • iOS points are used as an abstract unit for density independent pixels in which 1 iOS point is equal to 1 density independent pixel.

Android What is the difference between "px", "dip", "dp" and "sp"?

  • 1 android point does not equal 1 physical pixel on a 1x device.
  • 1 android point equals 1/72 of an inch.
  • 1 dp is used as a density independent pixel.

Web https://www.w3.org/Style/Examples/007/units.en.html

  • 1 CSS point does not equal 1 physical pixel on a 1x device.
  • Obviously CSS points are listed units are NOT RECOMMENDED.

Sketch

  • According to Sketch units are by default in points and 1 point is equal to 1 pixel.

InVision

  • 1 point is equal to 1 pixel.

I have also come across this formula:

pixel   = point * resolution (in terms of dpi) / 72

In which obviously the number of physical pixels in a point is variable...

So, my question is:

  • Why is 1 CSS point equal to 1.333 CSS pixels?
Jeffpowrs
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  • The answer is, because it was decided thusly. I don't think there is any more logical reason. – Mr Lister Nov 14 '18 at 18:02
  • @jonrsharpe I don't agree that this question is a duplicate of that question all the answers in that question are covered before I ask my actual question which is not answered in the previous question. – Jeffpowrs Nov 14 '18 at 18:29
  • @mr-lister I don't agree that this question is a duplicate of that question all the answers in that question are covered before I ask my actual question which is not answered in the previous question. – Jeffpowrs Nov 14 '18 at 18:29
  • I can't think of anything to say (in an answer) that hasn't been said in the answers in the linked questions already. A point is 1/72 inch and a pixel is 1/96 inch. You can keep repeating "yes, but why", but that won't gain you more insight. "That's how it was decided" is the best you can get. – Mr Lister Nov 15 '18 at 07:26

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