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Rolex 645
Last updated: July 27, 2025
Brand
Caliber Number
645
Production Period
1948 – 1955
Lignes
10.5”’
Diameter
23.7 mm
Height
6.35 mm
Power Reserve
Unconfirmed
Frequency
18,000 A/h (2.5 Hz)
Jewels
17 or 18
Escapement
Swiss Lever
Anti-Shock Device
Kif Flector
Hand Count
3
Manufacture Region
Unconfirmed
Functions
Automatic (Perpetual)
Rolex 645 Description
The Rolex Caliber 645 is a chronometer-grade automatic movement from the early 1950s “Semi-Bubbleback” era. As part of the larger 600-series, this 10.5”’ caliber was more robust and accurate than its predecessors, allowing Rolex to consistently feature the “Officially Certified Chronometer” designation on its dials. It was a time-only workhorse that helped solidify Rolex’s reputation for precision.
