You can replace most Casio watch batteries yourself with basic tools in about 10 minutes
Casio watches use standard coin-cell batteries that you can buy at any drugstore or hardware store for $3 to $8. The process is straightforward: open the case back, note which battery type your watch uses, swap in the new one, and close the case. You do not need to send the watch away or visit a jeweler unless the case back is glued shut or the watch is water-resistant and you want to maintain the seal.
The main variable is how your specific Casio opens. Some models have a screw-off case back (most common), some have a snap-off back, and a few have a sealed back that requires tools or professional service. This guide covers the screw-off and snap-off types, which account for the vast majority of Casio watches sold.
Key Takeaways
- Most Casio watches have a screw-off case back that opens with a coin or small flathead screwdriver in a counterclockwise turn.
- Write down the battery type printed on the old battery before you remove it, because you need the exact model number to buy the replacement.
- Coin-cell batteries cost $3 to $8 and are sold at drugstores, hardware stores, and online retailers.
- If your watch case back is glued or sealed, or if you want to preserve water resistance, take it to a jeweler or Casio service center instead of opening it yourself.
Gather your tools and identify your battery type
You need three things: a coin or small flathead screwdriver, the correct replacement battery, and a clean, flat work surface. Lay a cloth on the surface so small parts do not roll away. A magnifying glass or phone camera zoom helps if the battery type is hard to read.
Look at your watch case back — the metal or plastic disc on the back of the watch. If you see a slot or notch around the edge, it unscrews. If the back appears smooth with no slot, it may snap off instead. Either way, do not force it. If you feel strong resistance, stop and check the manufacturer information or take it to a jeweler.
Before you open the watch, look up your model number online or in the manual to confirm the battery type. Casio usually prints the model number on the case back itself. Once you open the watch, you will see the battery sitting in a small metal holder. The battery itself is stamped with a code like SR626SW, LR44, or CR2032. Write this code down — it is the exact part number you need to buy.
Remove the case back
Place the watch face-down on your cloth. Locate the slot or notch on the case back edge. If your watch has a screw-off back, insert your coin or screwdriver into the slot and turn counterclockwise — the same direction you turn to loosen a jar lid. Turn slowly and steadily. The back will come free after one or two full rotations.
If your watch has a snap-off back instead, look for a small notch or indentation. Insert a flathead screwdriver gently into the notch and explore light upward pressure. The back will pop off. Do not pry hard — if it does not move with gentle pressure, it may be glued or sealed, and you should stop.
Once the back is off, set it aside on your cloth where it will not roll away. You will now see the battery sitting in a metal holder or clip inside the watch. The battery is usually a thin, flat disc about the size of a dime or smaller.
Remove the old battery and install the new one
Look at how the old battery sits in its holder. Most Casio watches use a straightforward metal clip or spring that holds the battery in place. Gently lift one edge of the battery with your fingernail or a plastic tool — never use metal, which can damage the watch circuit. The battery will pop out. If it does not move easily, do not force it; stop and take the watch to a jeweler.
Before you throw away the old battery, confirm the type code one more time. This is your insurance against buying the wrong replacement. Common Casio battery types are SR626SW (silver oxide), LR44 (alkaline), and CR2032 (lithium coin cell). Buy the exact same type.
Slide the new battery into the holder with the positive side facing up — usually the side marked with a + symbol or the side that was facing up on the old battery. Press gently until the metal clip or spring holds it in place. The battery should sit flat and not rock. If it feels loose, lift it and reposition it until it sits snugly.
Close the case back and test the watch
Before you seal the watch, press the crown (the button on the side) or any other buttons to confirm the watch turns on or responds. If the watch has a digital display, it should light up. If it has hands, they may move or tick. This takes only a few seconds and confirms the new battery is working before you close everything up.
Once you confirm the watch works, place the case back on the watch. If it is a screw-off back, insert your coin or screwdriver into the slot and turn clockwise — the same direction you turn to tighten a jar lid. Turn until the back is snug but do not over-tighten, which can crack the plastic or strip the threads. You should feel slight resistance, then a small click or stop.
If it is a snap-off back, align the notch with the indentation on the watch body and press down firmly until you hear or feel a click. The back should sit flush with the watch case with no gaps.
When to take your watch to a professional instead
Do not open your watch yourself if the case back is glued shut, if the watch is advertised as water-resistant or waterproof, or if you see no clear slot or notch on the back. Glued backs require heat or special tools to open safely. Water-resistant watches have gaskets or seals that you can damage by opening them, and once damaged, the watch will leak if exposed to water or sweat.
If your watch is water-resistant and you want to maintain that protection, take it to a Casio service center or a jeweler who services watches. They will open the case, replace the battery, and re-seal it with a new gasket if needed. This costs $15 to $40 depending on your location and the watch model, but it preserves the water resistance.
If you open the watch and the battery holder is corroded, cracked, or the battery does not sit flat, stop. Corrosion or damage to the holder means the watch may not work reliably even with a new battery, and a professional should inspect it.
Common mistakes to avoid
The most common error is buying the wrong battery type. The code on the old battery is not optional — it is the only way to know what to buy. If you guess or buy a "universal" battery, you risk installing one that does not fit, does not power the watch, or drains too quickly.
The second mistake is over-tightening the case back. You do not need to turn hard. If you feel strong resistance, stop and turn back slightly. A screw-off back should close with gentle, steady pressure. Over-tightening can crack plastic backs or strip the threads so the back never seals properly again.
The third mistake is touching the battery contacts or the circuit board inside the watch with bare metal tools. Use plastic tools or your fingernail instead. Metal can cause a short circuit or leave corrosion that damages the watch.
Finally, do not assume your watch is not water-resistant. Even inexpensive Casio watches often have some water resistance. If you are unsure, look up your model number online or ask a jeweler before you open it.
Frequently Asked Questions
How much does a Casio watch battery cost?
Most Casio batteries cost $3 to $8 when you buy them at a drugstore, hardware store, or online. You can find them at CVS, Walgreens, Home Depot, Amazon, or eBay. Buy the exact type code from the old battery — do not buy a generic or multi-pack unless it includes your specific type.
Can I replace the battery if my watch is waterproof?
You can open a waterproof watch yourself, but you will lose the waterproof seal. If the watch is advertised as waterproof or water-resistant, take it to a jeweler or Casio service center instead. They will re-seal it with a new gasket after replacing the battery, which costs $15 to $40 but preserves the water resistance.
What if the case back will not open?
If you feel strong resistance or the back does not budge after gentle turning, stop when ready. The back may be glued, sealed, or stuck. Forcing it can crack the case or damage the threads. Take the watch to a jeweler or Casio service center. Do not use excessive force or heat.
How long does a Casio watch battery last?
Most Casio watch batteries last two to seven years depending on the battery type and how often you use features like the backlight or alarm. Silver oxide batteries (SR626SW) typically last longer than alkaline batteries (LR44). The manual for your watch model usually states the expected battery life.
Do I need to reset my watch after changing the battery?
Most analog Casio watches do not need a reset — they will straightforward start working again once the new battery is installed. Digital Casio watches may lose the time and date if the battery was completely dead. If that happens, press the Mode or Set button to access the time-setting menu and re-enter the correct time and date.