Watch Almanac
Casio

G-Shock GA-2100

Ref. GA-2100-1A1 · “CasiOak”

Case diameter
45.4 mm
Manufacturer spec
Lug-to-lug
48.5 mm
Manufacturer spec
Thickness
11.8 mm
Manufacturer spec
Lug width
—
Not published

Retail price $110 (US, Apr 2026)

Ideal fit
Wrist flat: 55.1 mmLug-to-lug: 48.5 mm

How the G-Shock GA-2100 wears

Its lugs add only 3.1 mm to the 45.4 mm case, against 7.1 mm typical across the almanac, so it wears smaller than its diameter suggests.

On our fit model it sits best on wrists from 6.75" to 8" (17.1–20.3 cm); below 6.75" the lugs start to reach the edge of the wrist.

At 11.8 mm thick it is slimmer than 70% of the 10 other digital watches we've measured, so it slides under a cuff more easily than most.

Will the G-Shock GA-2100 fit your wrist?

With a 48.5 mm lug-to-lug, here is how it wears across common wrist sizes. We estimate the flat top of each wrist from its circumference; measure yours for a closer answer in the fit finder.

WristFlat width (est.)Fit
6"47.2 mmLugs overhang
6.5"51.2 mmSnug, lugs near the edge
7"55.1 mmIdeal fit
7.5"59.1 mmIdeal fit
8"63 mmIdeal fit

Specifications

Reference
GA-2100-1A1
Collection
G-Shock
Status
In production
Introduced
2019
Case material
carbon / resin (Carbon Core Guard)
Crystal
mineral
Water resistance
200 m
Bezel
fixed
Dial
black
Strap / bracelet
resin strap
Weight
51 g
Style
Digital, Sport, Everyday

Movement

Caliber
Casio 5611
Type
quartz
Accuracy
+/-15 s/month

More G-Shock references

Watches that wear the same size

Other watches within 1.5 mm of its lug-to-lug.

Sources