Nepenthes macrophylla is known with certainty only from the summit area of Mount Trusmadi in Sabah, Borneo, despite the presence of a number of nearby peaks (such as Mount Pinesowitan) that fall within its altitudinal range. However, there are unconfirmed reports that it also grows on the summit of a neighbouring peak. Older sources list a number of different values for the altitudinal distribution of N. macrophylla, with some giving a narrow range of 2200-2400 m and others a much wider span of 2000-2600 m. It is now known that this species occurs between 2200 m and the summit at 2642 m.