The Perpetual Calendar Ref. 5320 is a wristwatch by Patek Philippe.

This model was presented in 2017. It has a white gold case, a gilded opaline rose gold dial and is equipped with the high-class manufacture movement 324 S Q.

The calendar displays are arranged in the characteristic manner of Patek Philippe perpetual calendar watches since 1941, with a twin in-line day/month aperture at 12 o’clock and a date indicated by a hand surrounding a moon-phase aperture at 6 o’clock. These are complemented by two round apertures: one for the day/night indication between 7 and 8 o’clock; and the other for the leap-year cycle between 4 and 5 o’clock — both of which are useful to adjust the calendar. The extremely accurate moon phases require a one-day correction only once every 122 years.