A calendar display device for a mechanical watch piece, including a first disk, the disk of days, carrying multiple series of inscriptions symbolizing the seven days of the week, a second disk, the disk of dates, carrying inscriptions symbolizing the date of the month, a third disk, the disk of months, carrying 12 inscriptions symbolizing the months of the year. One of the disk of days and the disk of dates acts as a dial by being fixed, whereas the other acts as a rotary disk by being arranged concentrically and rotatably in relation to the dial. The dial includes an aperture making it possible to see the inscription of the current month. A hand indicates simultaneously the date and the day of the week; and a direct kinematic link between the disk of months and the rotary disk provides automatic indexing.