You can replace a G-Shock battery yourself with basic tools in about 15 minutes, or take it to a watch repair shop for $10 to $30

Most Casio G-Shock watches use a standard coin-cell battery — usually CR2032, CR2025, or CR2016 — that you can buy at any drugstore for $3 to $8. The watch case opens with a small Phillips or flathead screwdriver, and the battery slides out and back in without soldering or special tools. If you are not comfortable opening the case yourself, a local jeweler or watch repair shop will do it for you in a few minutes, usually while you wait.

The whole process depends on which G-Shock model you own. Digital models with straightforward plastic cases are easiest to open. Analog models and those with metal cases sometimes require a case opener tool. Either way, the battery itself costs almost nothing — the time and care matter more than the money.

Key Takeaways

  • Most G-Shock watches use a CR2032, CR2025, or CR2016 coin-cell battery that costs $3 to $8 and lasts three to seven years depending on the model.
  • You need only a Phillips or flathead screwdriver to open the case and remove the old battery; no soldering or special knowledge is required.
  • If your model has a metal case or sealed back, a case opener tool ($5 to $15) or a professional repair shop ($10 to $30) is the safer choice.
  • Always note which side of the battery faces up before you remove it, because installing it backward will prevent the watch from working.
  • A watch repair shop, jeweler, or department store watch counter can replace the battery for you if you prefer not to open the case yourself.

Identify your battery type before you buy a replacement

The battery model number is printed on the back of your watch case or inside the case itself. Common G-Shock batteries are CR2032 (the most frequent), CR2025, and CR2016. The numbers refer to the size: CR2032 is 20 millimeters wide and 3.2 millimeters thick, while CR2025 is 20 by 2.5 millimeters. If you cannot read the number on your watch, search your model number on the Casio website or check the original manual — most manuals list the battery type on the first or last page.

Do not guess. Buying the wrong size will not fit in the battery compartment, and you will waste money. If you cannot find the model number, take a photo of the back of your watch and show it to a jeweler — they can tell you the battery type in seconds.

Open the case with a screwdriver or case opener

Most digital G-Shock models have a plastic case back held by three to five small screws. Use a Phillips head screwdriver that fits snugly into each screw — a screwdriver that is too small will strip the screw head and make it impossible to open. Turn slowly and gently. Once all screws are loose, the plastic back should lift off. Set the screws in a small dish so you do not lose them.

If your watch has a metal case back, a case opener tool makes the job much easier. This is a small metal disc with a slot that fits into the groove around the edge of the case back. You turn it counterclockwise, and the back unscrews. Case openers cost $5 to $15 online. If you do not have one and do not want to buy one, a watch repair shop will open it for you.

Some G-Shock models have sealed backs that are not meant to be opened by the user. If you cannot find any screws or grooves, or if the manual says "sealed case," do not force it. Take the watch to a repair shop instead.

Remove the old battery and note its position

Once the case is open, you will see the battery sitting in a small metal or plastic holder. Before you touch it, look at which side faces up — the positive side (marked with a + symbol) or the negative side (marked with a − symbol). Take a photo or write it down. This matters because a battery installed backward will not work, and you will have to open the case again.

The battery usually sits loosely in the holder and lifts out with your fingernail or a plastic spoon. Do not use a metal tool that could scratch the circuit board. Once it is out, set it aside. If the battery is stuck, a tiny drop of rubbing alcohol around the edge can help loosen it, but do not force it.

Insert the new battery the same way the old one faced

Take your new battery and place it in the holder with the same side facing up as the old one. Press gently until it sits flat. You should hear or feel a small click as it settles into place. Do not press hard — the battery should sit snugly but not require force.

Before you close the case, press a button on the watch to test it. The display should light up or the hands should move. If nothing happens, the battery is probably installed backward. Open the case again, flip the battery, and test once more. Once the watch works, you are ready to close the case.

Close the case and replace the screws

Line up the plastic or metal case back with the watch body. If it has screw holes, insert the screws one at a time and turn them clockwise with your screwdriver. Tighten them snugly but not so hard that you strip the plastic. If the back has a groove and you used a case opener, turn the opener clockwise until the back is tight.

Once the case is closed, press the buttons again to make sure the watch still works. The battery should last three to seven years depending on how often you use the watch and which features you use — backlighting and alarms drain the battery faster than a straightforward digital display.

When to take your watch to a repair shop instead

If your case back is sealed, glued, or has no visible screws or grooves, do not try to open it yourself. A jeweler or watch repair shop has the tools and experience to open sealed cases without damaging them. The cost is usually $10 to $30, and the shop will often replace the battery while you wait.

You should also visit a repair shop if you are uncomfortable using a screwdriver, if the screws are stripped or stuck, or if you accidentally damage the case back while trying to open it. A professional can often fix or replace a damaged case back for less than the cost of a new watch.

Frequently Asked Questions

How long does a G-Shock battery last?

Most G-Shock batteries last three to seven years. Digital models with straightforward displays last longer than analog models or watches with backlighting and alarms, which drain the battery faster. The manual for your specific model usually lists the expected battery life.

Can I use a different battery size if I cannot find the exact one?

No. A CR2032 will not fit in a compartment designed for a CR2025, and forcing it in can damage the watch. Always use the exact size listed on your watch case or in the manual. If you cannot find that size, a jeweler can order it for you.

What should I do if the watch still does not work after I replace the battery?

First, open the case and flip the battery to make sure it is facing the right direction. If that does not work, the battery may be defective — try a different new battery from a different store. If the watch still does not work, the circuit board or another internal part may be damaged, and a repair shop should examine it.

Is it safe to open a G-Shock watch myself?

Yes, if you have a plastic case back and a screwdriver that fits the screws properly. Work slowly, keep the screws organized, and do not force anything. Metal case backs and sealed cases are riskier — a case opener tool or a professional is safer for those.

Where can I buy a G-Shock battery?

Coin-cell batteries are sold at drugstores, supermarkets, hardware stores, and online retailers. They cost $3 to $8. Make sure you buy the exact size your watch needs — CR2032, CR2025, or CR2016. If you are unsure, show a photo of your watch to a jeweler and they can tell you which one to buy.