title: Define and calculate Apples definition of the unit point
body: <p>Apple writes in the <a href="http://developer.apple.com/library/ios/documentation/userexperience/conceptual/mobilehig/UEBestPractices/UEBestPractices.html#//apple_ref/doc/uid/TP40006556-CH20-SW20" rel="nofollow">user interface guidelines</a> that a tappable element should be at least 44 x 44 points. They provide an example of the calculator app for reference. When I measured the tappable buttons I got the height of 10 mm/38 px. Using tools I found online I converted this to approximately 29 postscript points.</p>
  
  <p>My question is what does Apple mean by 44 points? How do I convert this correctly?</p>