Comparison · Reviewed
GA-2100 vs GA-B2100: Battery CasiOak or Solar Bluetooth CasiOak?
Verdict
Choose the GA-2100 for the lowest price and a simple three-year battery; choose the GA-B2100 if you want Tough Solar charging and Bluetooth time sync in a case that is only 0.1 mm thicker and 1 g heavier.
GA-2100 vs GA-B2100 side by side
Casio's specifications for the stock GA-2100-1A1 and GA-B2100-1A.
| GA-2100 | GA-B2100 | |
|---|---|---|
| Display | Analog-digital | Analog-digital |
| Shape | Octagonal | Octagonal |
| Case size (L × W × H) | 48.5 × 45.4 × 11.8 mm | 48.5 × 45.4 × 11.9 mm |
| Thickness | 11.8 mm | 11.9 mm |
| Weight | 51 g (1.8 oz) | 52 g (1.8 oz) |
| Case | Carbon fiber–reinforced resin (Carbon Core Guard) | Carbon fiber–reinforced resin (Carbon Core Guard) |
| Water resistance | 200 m / 20 bar | 200 m / 20 bar |
| Power | Battery: SR726W × 2, about 3 years | Tough Solar (rechargeable): about 7 months of normal use, about 18 months in darkness with power saving on a full charge |
| Tough Solar | No | Yes |
| Multi-Band 6 | No | No |
| Bluetooth | No | Yes |
| Module | 5611 | 5689 |
| Launched | 2019 | 2022 |
| Casio U.S. list price | $110 | $165 |
Which one should you buy?
Choose the GA-2100 if
- You want the classic CasiOak at the lowest list price ($110 vs $165).
- You prefer a simple watch with no app or pairing.
- You want the widest choice of custom colorways and bezels, which mostly target the GA-2100.
Choose the GA-B2100 if
- You never want to replace a battery.
- You want automatic time from your phone and about 300 world time cities in the CASIO WATCHES app.
- You travel and want phone finder and easy watch setting.
What the GA-2100 and GA-B2100 have in common
- Same octagonal design, 48.5 × 45.4 mm case and Carbon Core Guard structure.
- Both are rated 200 m water resistant.
- Both are analog-digital with a double LED light.
GA-2100 vs GA-B2100: questions
Do GA-2100 bezels fit the GA-B2100?
Not automatically. The cases are nearly identical in size, but aftermarket parts are made per model, so check the listing or ask us before ordering.
Is the GA-B2100 worth the extra money?
If you dislike battery changes or want phone sync, yes. If you just want the look, the GA-2100 gives the same shape for $55 less at list price.
Not sure? Send us your wrist size and how you'll wear it; a person replies.
Sources
- Casio: GA-2100-1A specifications (official Casio, accessed October 25, 2026)
- Casio G-SHOCK (U.S.): GA2100: Slim & Tough Analog-Digital Watches (official Casio, accessed October 25, 2026)
- Casio: GA-2100K-1A specifications (battery, band size) (official Casio, accessed October 25, 2026)
- G-Central: G-SHOCK GA-2100 specifications (independent reference, accessed October 25, 2026)
- Casio G-SHOCK (UK): Are G-SHOCK watches waterproof or water resistant? (official Casio, accessed October 25, 2026)
- Casio (U.S.): GA-B2100-1A specifications (official Casio, accessed October 25, 2026)
- Casio (UK): GA-B2100-1A1 specifications (app features, band size) (official Casio, accessed October 25, 2026)
- G-Central: G-SHOCK GA-B2100 specifications (independent reference, accessed October 25, 2026)
- G-Central: G-Shock GA-B2100 with Tough Solar power and Bluetooth link (independent reference, accessed October 25, 2026)
- Casio G-SHOCK (UK): How do solar powered watches work? (official Casio, accessed October 25, 2026)