Oris Caliber 644

Brand	Oris
Caliber Number	644
In-House?	No
Base Caliber	ETA 2836-2
Movement Type	Automatic, self-winding mechanical
Lignes	11.5”’
Diameter	26mm
Casing Diameter	25.6mm
Height	5.05mm (unconfirmed)
Jewel Count	27
Beat Rate	28,800 vph, 4Hz
Lift Angle	50 degrees
Power Reserve	~38 hours
Rotor Style	Ball-bearing
Rotor Winding Direction	Bi-directional
Hand-Windable?	Yes
Anti-Shock Device	Incabloc
Balance	Glucydur
Hand Count	4
Functions	Central hours; central minutes; small seconds at 9:00; central pointer date hand
Hacking Seconds?	Yes
Country of Manufacture	Switzerland, Swiss made
Known Models	Oris Classic Pointer Date (Add your watch to the comments below…)

The Oris caliber 644 is an automatic watch movement with a small seconds subdial at 9:00 and a pointer date hand. This caliber is based on the ETA 2836-2 and was introduced as far back as 1997.

The 644 has the characteristic red rotor that Oris is known for.

Oris 644 VS 641:

There is a similar caliber 641 with the main difference being that the 641 is the certified chronometer (COSC) version of the 644.

644 VS 645:

Oris calibre 645 watches look like 644 powered watches from a distance, but upon closer inspection, the central pointer hand on the 645 is a pointer day, compared to the 644’s pointer date. The 645 has a datewheel with a date window at 3:00.

Additional Resources:

• More Oris calibers