You can change most Casio watch batteries yourself with a case opener and a fresh battery

Casio watches use standard coin-cell batteries that cost between $3 and $8, and most models let you open the case back yourself without tools beyond a cheap case opener. The process takes ten minutes: pop the case back, note which battery is inside, buy the same type, swap it out, and close the case.

If your Casio is solar-powered, has a screw-down case back, or is water-resistant and you want to keep it sealed, the steps differ — but even then, a jeweler or watch repair shop will do it for $10 to $25 if you'd rather not.

Key Takeaways

  • Most Casio watch batteries are standard coin cells (usually CR2032, CR2016, or SR626) that you can buy at drugstores, supermarkets, or online for under $10.
  • A plastic case opener costs $2 to $5 and is the only tool you need for watches with snap-on case backs; you do not need a jeweler's screwdriver or special equipment.
  • Write down or photograph the battery type before you remove the old one, because the number is printed on the battery itself and you need it to buy the replacement.
  • Solar Casio watches and models with screw-down case backs require different steps or professional help, so check your manual first if your watch looks unusual.
  • A jeweler or watch repair shop can change the battery for $10 to $25 if you are not comfortable opening the case yourself.

What battery your Casio uses and where to buy it

Open the case back and look at the battery itself — the type is printed on the top. Most Casio digital watches use CR2032 (the most common), CR2016, or SR626. Some older models use different types. Write down the exact number before you close the case again.

Buy the same type at a drugstore (CVS, Walgreens), supermarket, or online. A single battery costs $3 to $8. Do not buy a generic "watch battery" pack — buy the exact type your watch needs. If you cannot find it locally, Amazon, eBay, and Casio's own website all stock them. Check the expiration date on the package; a battery that expired years ago may not work properly. Fresh batteries last 5 to 10 years in most Casio watches, depending on the model and how often you use the backlight or alarm.

Tools you need and where to get them

You need a plastic case opener — a small, flat tool with a notch designed to pry open watch case backs. Do not use a knife, screwdriver, or coin, because these can scratch the case or slip and damage the watch. A plastic opener costs $2 to $5 on Amazon or at any watch supply site.

Some Casio watches have a small slot in the case back for a coin or flat tool. If yours does, you can use a dime or penny instead of buying an opener. Test it gently first to make sure it fits without forcing. You do not need a jeweler's screwdriver, magnifying glass, or any other special equipment. If your watch has a screw-down case back (rare for Casio digital watches, more common in Casio analog models), you will need a small screwdriver — but most Casio watches snap open instead.

Step-by-step: opening the case and removing the old battery

Lay the watch face-down on a clean, soft surface like a cloth or towel. This protects the crystal and keeps the watch steady. Look at the case back — you should see a small notch or slot around the edge.

Insert the plastic opener into the notch and gently pry upward. Do not force it. If the case back does not budge after light pressure, stop and check whether your watch has a screw-down back instead. Twist the opener slightly if needed, but do not hammer or explore sudden force. Once the case back pops off, set it aside where you will not lose it.

Look at the battery — it is a small, flat, silver or gold disc. The battery type is printed on the top. Write it down or take a photo before you touch anything else. Gently lift the battery out. Some watches have a small plastic tab or spring underneath — note how it sits before you remove the battery, so you can put it back the same way. If there is a gasket (a thin rubber ring) under the case back, leave it in place.

Installing the new battery and closing the case

Place the new battery into the same position, with the positive side (marked with a +) facing up. If there was a plastic tab or spring, make sure it sits under the battery the same way it did before. Do not force the battery — it should sit flat and level.

Press the case back down firmly until it snaps. You should hear or feel a click. If it does not snap, the battery may not be seated correctly — pop the case back off, check the battery position, and try again. Press a button on the watch to test it. The display should light up or show the time. If nothing happens, the battery may be dead (rare, but possible), or it may not be making contact. Pop the case back off, lift the battery slightly, and press it down again to may support good contact.

When to take your watch to a jeweler instead

If your Casio has a screw-down case back, do not pry it. Use a small screwdriver to unscrew it counterclockwise. If you do not have the right screwdriver or are uncomfortable with this, a jeweler can do it for $10 to $25.

If your watch is solar-powered, it does not have a replaceable battery — it charges from light. If it stops working, it may need professional service or a new solar panel, which is beyond a home repair. If your watch is water-resistant and you want to keep it that way, a jeweler should change the battery. They have the tools to reseal the case properly. If you open it yourself, water may eventually seep in. If the case back is stuck or you are not confident, a jeweler is the safer choice. The cost is low, and you avoid the risk of scratching the watch or damaging the gasket.

Troubleshooting: the watch still does not work

If the watch does not turn on after you install the new battery, first check that the battery is the right type. Look at the old battery again — if you bought the wrong replacement, that is the problem.

Next, make sure the battery is seated correctly. Pop the case back off, lift the battery, and press it down firmly. Sometimes a battery sits slightly crooked and does not make good contact. If there is a plastic tab or spring under the battery, make sure it is not bent or out of place. If the watch still does not work, the problem may be inside the watch itself — a broken circuit, a corroded contact, or a failed component. This is not a battery issue. Take the watch to a jeweler or contact Casio directly. Most Casio watches are inexpensive enough that repair costs may exceed the watch's value, so you may want to replace it instead.

Frequently Asked Questions

Can I use any CR2032 battery, or does it have to be a Casio brand?

Any CR2032 works. The battery type matters, not the brand. Duracell, Energizer, and generic batteries all perform the same. Buy whichever is cheapest and freshest at your store.

What if I lose the case back?

Contact Casio directly with your watch model number — they sell replacement case backs for $5 to $15. You can also check eBay or watch parts sites. Do not use the watch without a case back, because dust and moisture will damage the inside.

How do I know if my watch has a screw-down case back?

Look at the edge of the case back. A snap-on back is smooth or has a small notch. A screw-down back has visible screw slots or grooves around the edge. If you are unsure, check your watch manual or take a photo and ask a jeweler.

Is it safe to open my watch if it is water-resistant?

Opening it yourself may damage the water resistance seal. If your watch is water-resistant and you want to keep it that way, have a jeweler change the battery. If it is not water-resistant, opening it yourself is fine.

How often do I need to change the battery?

Most Casio watch batteries last 5 to 10 years. If you use the backlight or alarm frequently, the battery may drain faster. When the watch stops or the display dims, it is time for a new battery.