Miyota · 91 series
9100
A multifunction automatic combining day, date, month, 24-hour and power-reserve indications.
At a glance
- Type
- Automatic mechanical
- Display / complication
- Calendar + power reserve
- Architecture
- Automatic calendar with reserve indication
- Timebase
- 28,800 vph / 4 Hz
- Power reserve
- Approx. 40 h
- Movement height
- 5.52 mm
- Jewels
- 26
Reference sources reviewed 7 November 2026. Published specifications, not independent measurements. Versions and complete-watch specifications can differ; fields without a verified figure are omitted or identified.
What distinguishes it
Look beyond the reference.
The dial can show both calendar information and the mainspring’s remaining energy. The movement runs at 4 Hz and is 5.52 mm high, illustrating how extra indications change the package relative to a simple 9015.
For the enthusiast
Multiple calendar displays do not establish an annual or perpetual calendar. The manufacturer lists the individual indications; follow the movement’s operating instructions for correction rather than inferring automatic month-length handling.