Cc Bg 1920 1280
Miyota/Citizen Caliber 9051

Miyota/Citizen Caliber 9051

Manufacturer Citizen (Miyota)
Caliber Number 9051
Movement Type Automatic
Diameter 26mm
3.9mm thick (unconfirmed)
Vibrations Per Hour
28,800 bph
Shock System Parashock
Power Reserve
~42 hours
Lift Angle
51 degrees
Hacking? Yes
Hand-Windable? Yes
Rotor Winding Direction
Clockwise (uni-directional)
Hand Count
Functions Central hours; central minutes; central sweeping seconds; date calendar at 3:00
Country of Manufacture Japan
Known Brands
Citizen Promaster (ref: NB6004-08E); Citizen Promaster Mechanical Diver 1977 Challenger 200m reissue (ref: NB6021-17E, NB6021-68L); Citizen Series 8 aka 831 (ref: NB6010-81E, NB6010-81L, NB6012-18L) (Please add your watch in the comments below!)

The Citizen (Miyota) caliber 9051 is a 24 jewels 3-hand automatic movement based on the 9 series framework. This is an in-house (Citizen owns Miyota) movement, made in Japan.

Some of the topics covered in this caliber listing:

Anti-Magnetic Hairspring:

Citizen states that the caliber 9051 is anti-magnetic up to 16000 gauss.

In March 2021, Citizen launched a Promaster titanium diver powered by the caliber 9051. From the official announcement:

“The new Cal. 9051 movement uses anti-magnetic materials for the balance spring and surrounding components to boost the overall magnetic resistance of the watch. This new model is capable of maintaining performance even when placed 1 centimeter from a device emitting a magnetic field. The watch is also resistant to magnetic fields from everyday devices, including smartphones, and it can even be used aboard ships with magnetic compasses.” –source

On March 23, 2022, Citizen reiterated (almost word for word from the quote above) the magnetic resistant properties of the 9051 in the official press-release announcing the Promaster 1977 Challenger reissue.

Other watches with the 9051:

On November 5, 2021, the Citizen Series 8 line was launched with the “831” series of integrated bracelet dress watches containing the caliber 9051. If there are more models not mentioned here, please add them in the comments below.


Citizen (Miyota) claims the average accuracy of the calibre 9051 to be within -10 to +20 seconds per day (not to be confused with the caliber 9050 which offers an accuracy of -5 to +10 sec/day). This information is provided with a special note stating the following:

“Accuracy measured in a stationary position. Due to the characteristics of mechanical watches, daily accuracy may be outside stated figures due to variations in conditions of use (including length of time worn, the position of the watch, wrist movement, and the winding of the spring.” –source

Replacement Prices:

As of the writing of this post, the 9051 is only available in upcoming Citizen models and is not being offered for sale by Miyota yet.

Additional Resources:

Venus Caliber 178

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