The diameter of the Moon is 3,474 km. (Diameter of the Moon in miles: 2,159 miles) Need to put this in context? The diameter of the Earth is 12,742 km, so the Moon’s diameter is about 1/4 that of the Earth (27.3% to be exact). Need another comparison? The diameter of Jupiter’s moon Ganymede – … Continue reading "What is Diameter of the Moon?"