Seiko Caliber 8R28

Brand	Seiko
Caliber Number	8R28, 8R28A
Family	8R
In-House?	Yes
Movement Type	Automatic, Chronograph
Jewels	34
Power Reserve	45 hours
Vibrations Per Hour	28,800 bph
Parts	292
Hacking Seconds?	Yes
Hand-Windable?	Yes
Functions	Central hours; central minutes; central chronograph seconds; small running seconds at 3:00; 30 minutes counter at 9:00; 12 hours counter at 6:00; date at 4:30
Country of Manufacture	Japan
Known Models	Ananta SRQ011 (Add your watch to the comments below…)

The Seiko caliber 8R28 (aka 8R28) is an in-house automatic chronograph movement with 34 jewels, a power reserve of about 45 hours, and beats at 28,800 vph. As part of the 8R family of movements, the 8R28 features a vertical clutch and column wheel chronograph system. This movement is entirely made in Japan.

Average Accuracy Rating:

What can you expect as far as timekeeping?

Seiko official documentation claims that the average accuracy of the 8R28 is between -15 to +25 seconds per day in normal operating conditions and temperatures of 5C to 35C (41F to 95F).

Examples of watches with this caliber:

The caliber 8R28 pictured was found in a Seiko Ananta model SRQ011.

Additional Resources:

• Official 8R28 user manual (pdf)