Citizen Caliber B910: Classic Quartz Movement with Dual Calendar and 24-Hour Display

The Citizen Caliber B910 is a multifunction analog quartz movement offering three-hand timekeeping along with a day-date display and a 24-hour subdial. It’s designed for watches that blend functionality and symmetry, typically found in business casual or dressy timepieces with an elegant multi-subdial layout.

This caliber delivers precise quartz accuracy with a refined dial aesthetic, making it ideal for users who prefer analog clarity but appreciate having useful calendar tools at their fingertips.

Key Features

The B910 is structured to deliver clear, comprehensive time and date information in a traditional analog layout, featuring:

• Three-hand analog display: Hour, minute, and central seconds

• Date display: Usually via a hand or subdial

• Day of the week display: Retrograde or arc format

• 24-hour time subdial: Indicates AM/PM or military time

• Quartz movement: Powered by a silver oxide battery

• Accuracy: ±20 seconds per month

• Battery life: ~2 to 3 years

• No chronograph or alarm features

• Non-hacking seconds (second hand continues while setting time)

The layout is designed for easy readability, with subdials positioned to enhance dial symmetry and balance.

Retrograde and Subdial Displays

The B910 features a retrograde day-of-the-week indicator. Unlike a circular subdial, the retrograde day hand moves from Monday to Sunday in an arc, then snaps back to the beginning of the week. This design provides:

• A visually appealing display

• More room for other subdials

• A dynamic, animated element to the dial

The 24-hour subdial helps distinguish AM from PM, especially useful for travelers or those needing military time orientation.

Setting Instructions

The B910 uses a traditional crown and pusher setup, common to analog multi-calendar watches.

Crown Operation:

• Position 0 (pushed in): Normal timekeeping

• Position 1 (pulled halfway):

  • Turn to set the date (clockwise or counterclockwise depending on the model)

• Position 2 (fully pulled out):

  • Set time using hour and minute hands

  • The 24-hour subdial adjusts in sync with the main time

Pusher Operation (when present):

• A recessed day-correcting pusher (typically at 2 or 4 o’clock) adjusts the retrograde day display

• This is particularly useful when resetting the calendar after a battery change

⚠️ Do not attempt to change the date or day between 9:00 PM and 3:00 AM, as the internal gears may be engaged in the automatic change cycle and could be damaged.

Power Supply

• Battery type: SR621SW (1.55V silver oxide)

• Typical life: 2–3 years

• Signs of low battery:

  • Second hand stops or stutters

  • Subdials fail to update

Battery replacement should be performed by a professional to preserve case integrity and water resistance, especially in dress watches with snap-on or sealed casebacks.

Movement Construction

Internally, the B910 is built with:

• A robust quartz regulator circuit

• A stepper motor to drive the central hands

• A gear train for calendar transmission

• Subdial linkages that route to the 24-hour and day displays

This system is efficient and low-maintenance, requiring no oiling or regulation under normal conditions.

Design Integration and Watch Styles

Watches using the B910 typically feature:

• Dress or classic styling

• Case sizes from 38 mm to 42 mm

• Roman numerals or stick indices

• Symmetrical subdial placement (day at top left, 24-hour at bottom, date at right)

• Mineral crystal over the dial

• Water resistance rated 30M to 50M

• Leather straps or fine metal bracelets

These watches are often part of Citizen’s fashion-forward collections and appeal to those who appreciate both visual detail and functional design.

Ideal User

The B910 is perfect for:

• Style-conscious professionals who want both looks and practicality

• Travelers needing 24-hour AM/PM awareness

• Watch enthusiasts who enjoy retrograde motion

• Collectors of analog quartz calendar models

• Gift buyers looking for affordable elegance

This movement balances modern convenience and traditional charm, making it a versatile choice.

Summary

The Citizen Caliber B910 is a refined analog quartz movement that brings together day, date, and 24-hour indicators in a stylish, symmetrical layout. With its retrograde day display, accurate timekeeping, and compact design, it powers a range of watches that are both attractive and reliable. Perfect for everyday use or formal settings, the B910 continues to deliver functional beauty through proven quartz precision.