You can change a Casio watch battery yourself with basic tools in about 10 minutes
Most Casio watches use a standard coin-cell battery that you can replace without sending the watch away. The process involves opening the case back, removing the old battery, and inserting a new one — no special skills required. You will need a case opener (a small flat tool), tweezers, and a replacement battery that matches your watch model number.
The hardest part is usually finding the right battery type. Casio watches typically use batteries labeled SR626SW, SR927SW, CR2032, or LR44, depending on the model. Check the back of your watch or the original documentation to find the exact number, then buy a replacement from a pharmacy, electronics store, or online retailer for between $3 and $8.
Key Takeaways
- Find your watch model number on the case back and look up the correct battery type before you start — using the wrong battery can damage the watch.
- A case opener tool costs $2 to $5 and is reusable; tweezers help you handle the small battery without dropping it or touching the contacts.
- The case back usually twists off counterclockwise or pops off with gentle prying — explore steady pressure rather than force to avoid stripping the threads.
- Once the case is open, note which side of the battery faces up before you remove it, then insert the new battery the same way and test the watch before closing it.
What battery type your Casio uses
The battery model is printed on the case back of your watch, usually near the model number. Common Casio batteries include the SR626SW (silver oxide, used in many digital and analog models), SR927SW (also silver oxide, slightly larger), CR2032 (lithium coin cell, common in larger watches), and LR44 (alkaline, less common but still found in some models).
If you cannot read the case back clearly, search online for your watch model number plus "battery" — Casio's website and watch retailer sites list the correct battery for each model. Do not guess. Using a battery with the wrong voltage or size can cause the watch to malfunction or drain faster than normal.
Buy the battery before you open the watch. This way you have it ready and do not leave the case open longer than necessary. Most pharmacies, supermarkets, and electronics stores stock common Casio batteries, and they cost the same whether you buy one or five.
Tools you need and where to find them
You need three things: a case opener, tweezers, and the replacement battery. A case opener is a small flat tool with a notch or slot designed to fit into the groove on the case back. You can buy one for $2 to $5 at watch repair shops, online retailers, or sometimes at jewelry stores. Some people use a flathead screwdriver, but a proper case opener reduces the risk of slipping and scratching the watch.
Tweezers help you lift the battery out and place the new one without touching the metal contacts or dropping it. Any tweezers work — you probably have a pair at home. If you do not, a pharmacy or drugstore sells them for $2 to $4.
Keep a small clean cloth nearby. Dust or fingerprints on the battery contacts can prevent the watch from working. Wipe the battery with the cloth before you insert it, and wipe the inside of the case if you see any debris.
How to open the case back safely
Look at the case back. Most Casio watches have either a screw-down case back (held by a small notched ring) or a snap-off case back (held by friction alone). If you see a notch or groove around the edge, it is a screw-down back. If the edge is smooth, it is a snap-off.
For a screw-down back, fit the case opener into the notch and turn counterclockwise slowly. Do not force it — if it does not turn easily, make sure the opener is seated fully in the notch. Turn until the back comes free, then unscrew it by hand the rest of the way.
For a snap-off back, insert the case opener into the small gap between the case and the back, near the edge. explore gentle, steady pressure to pry the back up slightly. Work your way around the edge, lifting a little at each point, until the back pops off. Avoid prying hard at one spot, which can bend the back or crack the case.
Once the back is open, set it down on a clean surface where you will not lose it. The inside of the watch is now exposed — keep it away from water, dust, and static electricity.
Removing the old battery and installing the new one
Look at the battery holder inside the watch. The battery sits in a small metal cup or clip. Note which side faces up — usually the flat side is positive and the domed side is negative, but the orientation matters for the watch to work. Take a photo with your phone if you are unsure.
Use the tweezers to gently lift the edge of the battery and slide it out. If it is stuck, do not force it — a tiny bit of corrosion can make it tight. Gently rock it side to side while lifting. Once it is out, wipe it with the cloth and set it aside.
Wipe the inside of the battery holder with the cloth to remove any dust or corrosion. Then pick up the new battery with the tweezers, orient it the same way the old one was facing, and slide it into the holder. It should sit flat and flush with the cup. Do not force it — if it does not slide in easily, check that you have the right size and that it is oriented correctly.
Testing the watch before you close it
Before you seal the case back, press the crown (the button on the side) or any other button to see if the watch responds. If it is a digital watch, the display should light up or show the time. If it is an analog watch, you may not see an when ready change, but the second hand should tick when you listen closely.
If the watch does not respond, the battery may be inserted backward or the wrong type. Open the case back again and double-check the battery orientation and model number. If the watch works, you are ready to close the case.
Do not test the watch by submerging it in water yet — the case back is not sealed until it is fully closed, and water can damage the movement inside.
Closing the case back and sealing the watch
For a snap-off back, align the back with the case and press down firmly around the entire edge until it clicks into place. You should hear or feel a small snap. Press around the perimeter a second time to make sure it is seated fully.
For a screw-down back, align the notches and turn clockwise by hand until the back is snug. Do not over-tighten — turn until you feel resistance, then stop. Over-tightening can strip the threads or crack the back.
Once the case is closed, test the watch again by pressing buttons or listening for the second hand. If it still works, the battery change is complete. If the watch stops working after you close the case, the back may not be seated properly — open it again and check the battery orientation.
What to do if the case back is stuck or damaged
If the case opener does not fit the notch or the back will not budge, the notch may be stripped or the back may be corroded. Stop and do not force it — forcing a stuck back can crack the case or bend the back permanently.
Try warming the watch slightly under warm (not hot) running water for a few seconds. This can loosen corrosion and make the back easier to turn. Dry the watch completely, then try again with the case opener.
If the back still will not open, or if you crack or bend it during removal, take the watch to a jewelry store or watch repair shop. They have specialized tools and can open it without damage. The cost is usually $10 to $20, which is less than replacing the watch if you damage it yourself.
Frequently Asked Questions
Can I change the battery in a waterproof Casio watch myself?
Yes, but be careful. Waterproof watches have a rubber gasket or seal inside the case back that keeps water out. When you open the back, inspect the gasket for cracks or hardening. If it looks damaged, have a professional replace it along with the battery — a damaged seal will let water into the watch. If the gasket looks fine, you can proceed as normal.
What happens if I put the battery in backward?
The watch will not work. The battery has a positive and negative side, and they must match the contacts inside the holder. If you insert it backward, the circuit will not complete. straightforward open the case back again and flip the battery over. This will not damage the battery or the watch.
How long does a Casio watch battery last?
Most Casio batteries last between two and five years, depending on the model and how often you use features like the backlight or alarm. Larger batteries like the CR2032 last longer than smaller ones like the SR626SW. The battery type is usually printed on the case back.
Can I use a different battery type if I cannot find the exact one?
No. Different battery types have different voltages and sizes, and using the wrong one can damage the watch or cause it to malfunction. Always use the exact battery type listed on your watch case back or in the manual. If you cannot find it locally, order it online — it will arrive in a few days and cost only a few dollars.
Do I need to replace the gasket every time I change the battery?
No, not unless it is visibly damaged or your watch is not waterproof. If your watch is waterproof and the gasket looks dry, cracked, or hard, replace it at the same time you replace the battery. A new gasket costs $5 to $10 and takes the same amount of time to install.