Choose the GMA-S2100 if you want a lighter resin-and-carbon watch; choose the GM-S2100 if you prefer a metal-covered look. Casio’s published specifications make the GM-S2100 slightly shorter and narrower, but the GMA-S2100 is 0.2 mm thinner and 14 g lighter. Both are shock resistant and rated to 200 meters, and neither of these basic models is listed with solar charging or Bluetooth connectivity.
GMA-S2100 vs. GM-S2100 at a glance
The examples below are the GMA-S2100-7A and GM-S2100-3A. Specifications can vary by regional listing or exact model suffix, so check the product page for the colorway you intend to buy.
As an Amazon Associate I earn from qualifying purchases.
| Specification | GMA-S2100-7A | GM-S2100-3A |
|---|---|---|
| Case size (L × W × H) | 46.2 × 42.9 × 11.2 mm | 45.9 × 40.4 × 11 mm |
| Weight | 41 g | 55 g |
| Case/bezel materials | Carbon / resin | Resin / stainless steel |
| Band | Resin | Resin |
| Shock resistance | Yes | Yes |
| Water resistance | 200 m | 200 m |
| Power and connectivity | Battery powered; no Bluetooth/app connectivity listed | Battery powered; no Bluetooth/app connectivity listed |
Sources: Casio’s India 2100-series comparison, international GMA-S2100-7A specifications and Europe GM-S2100-3A specifications. The comparison chart is localized for India; its prices are not global prices and are not needed to distinguish these watches.
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWhat differs between the two watches?
Weight and materials
The GMA-S2100 weighs 41 g, compared with 55 g for the GM-S2100, according to Casio’s product specifications. The GMA combines carbon and resin in the case and bezel, with a resin band. The GM combines resin and stainless steel in the case and bezel, also with a resin band. The GM-S2100 is categorized as metal covered, but it is not a full-metal watch: its band remains resin.
#1 Best Overall
- This high-quality watch has a black plastic strap (21 cm length and 20 mm width) with a pin buckle
- Case diameter: 40 mm, case height: 11 mm, case colour: black. Dial colour: black
- Waterproof: 20 bars -Weight: 42 g
- International products have separate terms, are sold from abroad and may differ from local products, including fit, age ratings, and language of product, labeling or instructions.
Dimensions and wrist presence
The GM-S2100 measures 45.9 × 40.4 × 11 mm, while the GMA-S2100 measures 46.2 × 42.9 × 11.2 mm. In those listed dimensions, the GM is shorter and narrower; the GMA is 0.2 mm thinner. Those measurements describe the cases, not how either watch will fit an individual wrist. Wrist shape, strap adjustment and personal preference affect perceived fit, and no comparative wear test is established here.
What features do they share?
Casio’s catalog lists both models with shock resistance, 20-bar (200-meter) water resistance, hand-shift, world time, a stopwatch, countdown timer, alarms and a double LED light. The family chart lists 31 world-time zones for these basic models. The catalog dates to 2022; confirm the exact suffix’s current product page for specifications before purchase.
Rank #2
- Casio G-Shock Alarm World Time Quartz Analog-Digital Ladies Watch GMA-P2100ST-4ADR
Battery power, not solar or Bluetooth
Casio lists the GMA-S2100-7A as running for approximately three years on two SR726W batteries. The 2100-family comparison chart shows the basic GMA-S2100 and GM-S2100 as battery-powered without Bluetooth/app connectivity or solar power; those features appear on other branches of the 2100 family. A metal cover does not indicate upgraded electronics. If phone connectivity or solar charging is essential, compare the specific 2100 variant that lists the feature rather than assuming it comes with either watch discussed here.
Free tools Windows power users keep installed
One-click scans. No signup required.
Which one should you choose?
Choose the GMA-S2100 if you value lightness
At 41 g, it is the lighter option by 14 g. Its carbon-and-resin case and bezel construction and resin band make it the straightforward pick if reducing weight matters more to you than a metal-covered finish.
Rank #3
- ●Impact-resistant structure
Choose the GM-S2100 if you want a metal-covered look
Its stainless-steel component gives the case and bezel a more metal-forward appearance while retaining a resin band. Choose it for that finish, not because it is a full-metal watch or has different listed toughness ratings.
Choose by measurements if case size is your priority
The GM-S2100’s listed case is shorter and narrower, whereas the GMA-S2100 is marginally thinner. There is no universal fit winner in those figures alone; consider the dimensions together with the resin strap and how you prefer a watch to sit on your wrist.
Quick Recap
Best Value
- Case size (L W H): 48.5 45.4 11.8 mm
- Case and bezel material: Carbon / Resin
- Construction: Shock Resistant Carbon Core Guard structure
- Weight: 51 g
- Water resistance: 200-meter water resistance
Rank #4
- {"bullet_point1":"clip-on"}
- The rugged watch's 45.4mm case is expertly crafted from fine resin mixed with carbon fiber, an innovative composition that is lighter and more durable than resin
- The smooth black dial features an analog-digital display and double LED light feature, for easy visibility in the dark
What to verify before buying
- Confirm the full model suffix and color, since regional listings and variants can differ.
- Check the exact product page for its dimensions, weight and features instead of relying on the family name alone.
- Decide whether you prefer the GMA’s lower listed weight or the GM’s metal-covered appearance; both use resin bands.
- If you need solar power or Bluetooth/app functions, make sure the exact 2100 model explicitly lists them.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →
