What does DisplayMetrics.scaledDensity actually return in Android?

Question

I\'m trying to understand the sp unit in Android, but I can\'t really figure out how it works. The documentation say:

sp

Scale-independent Pi

Answer 1

Scaled density is a unit of measurement not a value of font-size. Let me try to give you an example, feel free to follow up with a comment if you would like more explanation.

Say you have a font size 18sp. This needs to get converted to pixels in order to display on the screen. The following calculation is made: pixels = fontSize * scaledDensity * scale. Now, when you change your phone's settings, you are changing the scale. This results in the same calculation being made, but let's say with a scale of 1.5 now instead of 1. The unit of scaledDensity is not changed because your screen's pixel density has not changed.

I hope that helps!