Minimum screen areas
It is always important to determine the minimum size of an active element for your game. The comfort of playing directly depends on this factor. The average width of an adult human male finger varies from 15 to 20 mm, the average index finger width is 20 mm or 0.75 inch. In ancient times, this size was used as a measurement of length called finger or digit (in Latin digitus means finger). Let's convert finger into pixels, all we need for this is simple math; the digital length of the screen in pixels should be divided into the physical length of the screen in millimeters its size in pixels, so we will get the number of pixels in one millimeter. The conversion is shown as follows:
iPhone: 480 px/75 mm is approximately 6.41 pixels per mm (163 ppi)
iPhone (Retina): 960 px/75 mm is approximately 12.83 pixels per mm (326 ppi)
iPad: 1024 px/197 mm is approximately 5.20 pixels per mm (132 ppi)
iPad mini: 1024 px/160 mm is approximately 6.41 pixels per mm (163 ppi)
iPad mini (Retina...
