Citizen Caliber G620M & G670: Eco-Drive Simplicity with Calendar Precision

The Citizen G620M and G670 calibers are part of Citizen’s reliable Eco-Drive analog movement lineup, known for combining clean aesthetics, calendar functionality, and solar-powered convenience. These movements are designed for users who appreciate hassle-free maintenance, accurate timekeeping, and elegant analog style.

With minimalistic interfaces and robust construction, the G620M and G670 are often found in Citizen's classic dress and everyday watches. Their greatest appeal lies in long-term reliability with no battery replacements needed.

Key Features

Both the G620M and G670 offer similar specifications with minor variations in design integration. These movements are known for:

• Eco-Drive solar-powered technology

• Analog 3-hand timekeeping (hours, minutes, seconds)

• Date display at the 3 o'clock position

• Perpetual calendar (G670 only) or standard calendar (G620M)

• Battery-free operation (powered by light)

• Power reserve: Up to 6 months on a full charge

• Accuracy: ±15 seconds per month

• Quick date correction via the crown

• Durable quartz-regulated movement

The movements are often housed in sleek, low-profile cases, making them ideal for office wear, formal events, or daily routines.

Eco-Drive Technology

Both movements utilize Citizen’s renowned Eco-Drive system, which converts light (natural or artificial) into energy.

• Light source charges a solar panel beneath the dial

• Energy is stored in a rechargeable cell—not a disposable battery

• Watch continues to run for months in darkness

• Reduces battery waste and the need for regular maintenance

Charging Overview:

• Sunlight: ~2-4 hours of full sunlight = full daily charge

• Artificial light: Takes longer but still effective

• Full charge reserve: ~6 months without additional exposure

This system is ideal for eco-conscious users and those who don’t want to worry about battery changes.

Calendar Functions

• The G620M provides a standard date display.

  • Requires manual correction at the end of months with fewer than 31 days.

• The G670, however, offers a perpetual calendar, which:

  • Automatically adjusts for months with 28, 29, 30, or 31 days

  • Includes leap year logic

  • Requires no manual intervention once set

This distinction makes the G670 ideal for users who want an entirely “set-and-forget” timepiece.

Crown Operation

These calibers use a standard pull-out crown for setting time and date.

Crown Positions:

• Position 0 (pushed in): Normal operation

• Position 1 (half-pulled):

  • Rotate clockwise to change the date

• Position 2 (fully pulled):

  • Adjust hour and minute hands

When setting the date, it's best to avoid doing so between 9:00 PM and 3:00 AM, as the internal gears may be engaged in the automatic date change process.

Design & Application

Watches using the G620M and G670 are typically designed for elegance and everyday wear. Common characteristics include:

• Slim stainless steel cases or two-tone finishes

• Minimalist dials with baton or Roman numeral indices

• Leather straps or stainless steel bracelets

• Water resistance ranging from 30M to 100M

• Mineral or sapphire crystals, depending on the collection

These watches cater to a wide demographic, from professionals to seniors, due to their legibility and simplicity.

Accuracy & Maintenance

Citizen’s quartz accuracy ensures time drift remains negligible for most users. Maintenance is minimal:

• No battery changes needed for 10+ years

• Occasional cleaning of case and bracelet recommended

• Recharge periodically if stored in the dark for extended periods

If the power reserve is depleted, simply place the watch in direct sunlight for a few hours to restore full function.

Ideal User

These movements suit:

• Busy professionals who want reliability and style

• Elderly wearers seeking clarity and ease-of-use

• Eco-conscious consumers avoiding disposable batteries

• Minimalist enthusiasts who favor clean designs with quiet performance

• Gift-givers—Eco-Drive watches with these movements are low-maintenance and long-lasting

Summary

The Citizen Caliber G620M and G670 represent the essence of modern quartz timekeeping—low maintenance, stylish, and powered by light. Whether you choose the basic G620M with manual date adjustment or the G670 with its fully automated perpetual calendar, you’re getting a watch movement that embodies efficiency, accuracy, and environmental care.

With a 6-month power reserve and timeless design, these Eco-Drive calibers are excellent choices for those who want their timepiece to work silently and reliably in the background of everyday life.