Device Independent Pixel (or Density Independent Pixel) count is
a very important factor when dealing with mobile devices. Many
people only focus on the physical size of the screen, but the
dot per inch (DPI) is what gives the screen depth. So what
exactly does this mean for a mobile device? Word to the wise,
you are going to need to put on technical propeller hats
required for this blog post. There will be math involved. You
have been warned. Device Independent Pixel Formula: DPI
Explained DPI is a term that originated with print, and is
sometimes referred to as PPI (pixels per inch) when dealing with
computer software. Windows computers have a default DPI
calculated to 96 DPI, while Macs use 72 DPI. On the web on a
desktop computer all browsers unify the display at 72 DPI.
Mobile devices are another matter entirely. A mobile device will
first start by determining the real DPI for the device and then
will round that number to the to a 120 DPI for a low density
screen, 160 DPI for a medium density screen (whi