Quite often when rating a film's success, the numbers often quoted are the budget of the film vs the amount earned at the Box Office.
However, the money made at the Box Office is the total ticket sales, which of course includes the cinema's own cut as well as the costs of distribution, etc. So to know if a film is a success you can't just compare the Box Office earnings to the films production cost. An $80,000,000 budget vs $100,000,000 "at the box office" does not mean a $20,000,000 profit.
So why is it reported this way, and how can we really tell if a film made a profit? Is there an average percentage of the Box Office earning that we can use to work out if the film was actually financially successful?