Does anyone know how to work out how much mortgage you can afford?

Does anyone know how to work out how much mortgage you can afford roughly? me & my fiancee are 1st time buyers but dont know what to look for, got an appointment with bank but thats not till next monday, need an estimated price range. many thanx 2 all the reply.
Answer
Google "mortgage calculator." there are a numbe rof websites with such things available.