G-Shock model number checker, read part by part

On the caseback. Casio's own support page says the model number is marked on the back cover of the watch, as letters and numbers joined by a hyphen. The caseback usually shows only the series part, such as GW-M5610U or DW-5600E, and the box and the tag print the full name with the color digit, such as GW-M5610U-1. The four digit number beside it on the caseback, usually in a small frame, is the module number.

It is the number of the movement inside the watch, four digits such as 3229 or 5611, usually engraved in a small frame on the caseback to the left of or above the model name. Casio files its instruction manuals by this number, which is why the checker sends you to Casio's own manual for it. The tag and the manual carry it too.

Casio does not publish a key, and collectors say the naming is not fully consistent. The parts that two independent sources agree on are these. DW is a digital, battery powered model. GW is Waveceptor: Tough Solar, Multi Band radio time sync, or both. GM is Metal Covered, a metal bezel over resin, and GMW is full metal. A B before the number means Bluetooth, an S a smaller case, and an M on GW models usually Multi Band. After the number, D, T and L mean a steel bracelet, a titanium bracelet and a leather strap. Other letters, such as E or U, have no published meaning.

Collectors read the first digit after the hyphen as the main color: 1 usually black, 2 blue, 3 green, 4 red, 5 brown, 6 purple, 7 white, 8 gray and 9 yellow or gold. A letter after it, such as A or B, tells variants within that color apart, and a second digit, as in GA-2100-1A1, the color of the hands or the display. This is a collector convention, not a Casio key, so the checker says usually, and Casio's page for your model is the place to confirm the color.

They are market codes printed on the box and the tag, not on the caseback. Collectors read ER as Europe, JF as Japan, JR as a Japan limited release and DR as export to regions without a Casio distributor. A lone V, as in DW-5600E-1V, is read as an export version. Collectors disagree on some other codes, such as CR, so the checker leaves those unread. A market code says where a watch was meant to be sold, not where it was made.

Not a G-Shock serial number Casio publishes a meaning for. The model name and the module number are shared by every watch of that model. Tough Solar models also carry a short code on the caseback, such as 202A 246 E, which collectors read as a factory, a day of the year and a year letter. Casio has not published that reading, and the year letter repeats every ten years, so the checker does not read it and the page does not date watches from it.

Not from the model name or the module number. Neither carries a date. The module number can narrow the period a little, because Casio sometimes moves a model to a new module, as when the GW-M5610 moved from module 3159 to 3495 in 2021 and the GW-M5610U name followed. That tells you which version you have, not the year it was made.

Not by itself. One model can carry more than one genuine module over the years: the DW-5600 has used 3229 and later 3525, and in the United States the updated square solar model was sold under the older name for a while. Open Casio's manual for the number on your caseback and check that it describes a watch like yours, with the same functions, buttons and display.

No. Both are printed on Casio's own pages and copied onto counterfeit casebacks, so a well-formed number proves nothing. Collectors point to other things that fakes get wrong: a caseback that bulges, shallow or blurry engraving, and a missing module number. Those are reasons to look closer, not proof either way.

Casio offers no public lookup that confirms a watch is genuine from its numbers. Its advice, in a statement on counterfeits, is to buy only from authorized retailers. What Casio does publish is the manual for each module, which is what the checker links to.