title: Android screen density dpi vs ppi
body: <p>According to the android documentation, density should be in <strong>dpi</strong> (dots per inch) and all layout measurement should be in <strong>dp</strong>.</p>
  
  <p>and using a simple formula android can map <strong>dp</strong> to actual pixels.</p>
  
  <pre><code>px = dp * (dpi / 160), 
  160dpi ~ medium density screen which is the baseline
  </code></pre>
  
  <p>So why not just use <strong>ppi</strong> (pixels per inch) to describe screen density ?</p>