why are pizza boxes usually sqare shaped when the pizza is actually a circle?

Question: why are pizza boxes usually sqare shaped when the pizza is actually a circle?
- Keywords:
  circle,
  pizza,
  square
Asked by rosieredxxx to Sam on 24 Jun 2013.
- Sam Geen answered on 24 Jun 2013:
  
  It’s easier to make a square box than a round box, I suppose. For example, folding the edges of the lid is easier if it’s a square. But you’re right that it wastes some cardboard, even if they cut a hole in the box to put dipping sauce in.

Question: why are pizza boxes usually sqare shaped when the pizza is actually a circle?