Work out movie marathon time instantly with clear inputs, formula shown and shareable results.
Marathon length is films times runtime plus breaks between them — note that six films have only five gaps. At two hours a film with twenty minute breaks, a six-film marathon runs over fourteen hours, which is why start time matters.
Marathon length
total = films x runtime + (films - 1) x break length
Because no break is needed after the last film. Using the film count overstates the total by one break.
Most groups fade after four films or roughly nine hours. Longer marathons need meals, a change of position and genuinely long breaks.