title: Calculating image size in inches or dpi from pixels using php
body: <p>I need to calculate an approximate image size in inches assuming 300dpi.</p>
  
  <p>I have a target image size in mind, and i want to show the user if the image they have uploaded is adequate, or will need to be stretched, and offer various conditional messages based off of this.</p>
  
  <p>I already have the height and width in pixels, just need to know the math i guess.</p>