Casio G-Shock GA-B2100 — “Casio Oak” upgrade with Bluetooth and Solar Power

GA-B2100-2A — Updated April 2022 color! Buy it on Amazon!

GA-B2100 Model Range *may be updated

Quick Content Guide

  1. GA-B2100 Model Range *in different colors and bands
  2. General information about the watch *year of first release, model range etc.
  3. G-Shock GA-B2100 Display Guide *for key functions only
  4. G-Shock GA-B2100 on the wrist *only images and only on the wrist
  5. GA-B2100 Usage Patterns *what the watch is usually meant for
  6. Other G-Shock GA Watches *similar by price and functions but different by cases
  7. Official GA-B2100 Specs *all details and for base version GST-B400-1A
  8. Recent News about GA-B2100 *the latest breaking news and videos

General Information

*average Amazon Price, we may earn commission from purchases
Year of first Release2022
Suitable for Wrist Size145 – 215 mm
Module Number5689 / Manual
Model RangeOctagon
Battery TypeSolar (G-Shock Batteries)
Other Divisions the GA-B2100 belongs to: *you may find all watches of the division by clicking on the linkG-Shock Ana-Digi
G-Shock Bluetooth
G-Shock Carbon Core Guard
G-Shock For Small Wrists
G-Shock Solar
G-Shock 2022

Return to the Content Guide ↑

G-Shock GA-B2100 Display Guide *for key functions only. For you to know how it works))

General Display

  1. Hour hand
  2. Minute hand
  3. Mode hand
    Indicates the current mode. In the Timekeeping mode, this hand shows the current charge level.
  4. LCD

Shifting Hands to Read the Digital Display

Hand shift moves the hands out of the way for easy viewing of display information.

Phone Finder

You can use phone finder to trigger a tone on the phone to make it easy to find. The tone is forced to sound even if the phone is in vibrate mode.

Checking World Time

Enter the World Time.
After the currently selected World Time City name appears, the watch will display the current time in that city.

Return to the Content Guide ↑

G-Shock GA-B2100 on the wrist!

GA-B2100 Usage Patterns *what the watch is usually meant for

Return to the Content Guide ↑

What we like in GA-B2100 *comments by experts with 10 years experience in writing about Casio watches
— Carbon Core Guard structure (protects the module by enclosing it in a carbon case. The case is made of fine resin embedded with carbon fibers for outstanding strength and crack resistance)
Tough Solar (CASIO’s original solar-charging system converts not only sunlight but also light from fluorescent lamps and other sources into power)
G-SHOCK Connected App (you may manage all watch settings through your phone)
— 200-meter water resistance (good for swimming but not for deep diving)

Return to the Content Guide ↑

Other G-Shock GA Watches *similar by price and functions but different by cases

These are not all G-Shock GA Series. Here is a list of All G-Shock GA Watches →

Return to the Content Guide ↑

Official Casio Description.

Upgrade the retro look you love with the octagonal GA-2100 line, which inherits the design concept of the very first G-SHOCK, but now with Smartphone Link and Tough Solar power.

Official GA-B2100 Specs / Features *for base version GA-B2100-1A

  • Case size: (L× W× H)48.5 × 45.4 × 11.9 mm
  • Weight: 52 g
  • Case / bezel material: Carbon / Resin 
  • Band: Resin
  • Construction:
    Shock Resistant
    Carbon Core Guard structure
  • Water resistance: 200-meter water resistance
  • Power supply and battery life: Tough Solar (Solar powered)
  • Smartphone Link feature: Mobile link (Wireless linking using Bluetooth®)
  • App connectivity feature:
    Auto time adjustment
    Easy watch setting
    Approximately 300 world time cities
    Time & place
    Phone finder
  • Glass: Mineral Glass
  • Other: Neobrite
  • World time: World time 38 time zones (38 cities + coordinated universal time), city code display, city name display, daylight saving on/off, auto summer time (DST) switching, Home city/World time city swapping
  • Stopwatch:
    1/100-second stopwatch
    Measuring capacity: 00’00”00~59’59”99 (for the first 60 minutes) 1:00’00~23:59’59 (after 60 minutes)
    Measuring unit: 1/100 second (for the first 60 minutes) 1 second (after 60 minutes)
    Measuring modes: Elapsed time, lap/split time
  • Timer: Countdown timer
    Measuring unit: 1 second
    Countdown range: 60 minutes
    Countdown start time setting range: 1 second to 60 minutes (1-second increments and 1-minute increments)
  • Alarm/hourly time signal:
    5 daily alarms
    Hourly time signal
  • Light: Double LED light LED light for the face (Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow) LED backlight for the digital display (Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow)
  • Calendar: Full auto-calendar (to year 2099)
  • Mute feature: Button operation tone on/off
  • Energy saving feature: Power Saving (display goes blank to save power when the watch is left in the dark)
  • Battery display/alert: Battery level indicator
  • Run time: Approx. battery operating time: 7 months on rechargeable battery (operation period with normal use without exposure to light after charge) 18 months on rechargeable battery (operation period when stored in total darkness with the power save function on after full charge)
  • Accuracy: ±15 seconds per month (with no mobile link function)
  • Other features:
    Hand shift feature (Hands move out of the way to provide an unobstructed view of digital display contents.)
    12/24-hour format
    Date/month display swapping
    Day display (days of the week selectable in six languages)
    Regular timekeeping: Analog: 2 hands (hour, minute (hand moves every 20 seconds)), 1 dial (battery level, mode) Digital: Hour, minute, second, pm, month, date, day

Return to the Content Guide ↑

Recent News about GA-B2100 *on

RSS Error: A feed could not be found at ``; the status code is `403` and content-type is `text/html; charset=utf-8`

Return to the Content Guide ↑

Not sure about GA-B2100? There are more G-Shocks!

Back to All G-Shock Models →