Movie grosses reporting isn't an exact science. Studios and distributors have started disclosing detailed figures only recently; the information for films released over 15 years ago are therefore very sketchy. The longer you go back in time, the less reliable the information becomes.
Some sources often erroneously report theatrical rentals as grosses. On some old or foreign films, only rental figures may be available instead of grosses, and vice-versa.
The info on movie budgets is even harder to find: studios are usually very reticent when it comes to discussing how much a film cost, especially when a movie performed poorly at the box-office. Additionally, reported budgets may change over time due to escalating costs (Waterworld and Titanic are two high profile examples) or costs may be difficult to calculate (the salary for a star or director may be part of a sum agreed for a package deal consisting of several films).
Reported budgets may also vary greatly depending on whether they only include the cost of producing/shooting the film (the so-called 'negative cost') or also additional expenses (like prints and advertising). For low-budget movies, the promotional expenses can often be much larger than the negative cost (see for example The Blair Witch Project).
Whenever possible/available, our budget figures refer to a film's negative cost, unless otherwise indicated.
