You can change most watch batteries yourself with a case opener and a new battery
A watch battery typically lasts two to five years depending on the watch type and how often you wear it. When it dies, you have two choices: pay a jeweler or watch shop $15 to $50 to replace it, or do it yourself for $5 to $15 in parts and about ten minutes of time. The process is straightforward if your watch has a removable case back — most do. If your watch is sealed or has a screw-down crown, a jeweler is the safer choice.
The tools you need are inexpensive and reusable. A case opener (also called a case knife or case wrench) costs $5 to $20 and works on hundreds of watches. A battery costs $2 to $8 depending on the size. You may also need tweezers and a small flathead screwdriver, though most people have these at home. The hardest part is not the battery swap itself — it is opening the case back without scratching your watch.
Key Takeaways
- Most watch batteries cost $2 to $8 and last two to five years before needing replacement.
- A case opener tool costs $5 to $20 and works on most watches with removable case backs.
- The entire battery swap takes about ten minutes once you have the right tools and the correct battery size.
- Sealed watches and watches with screw-down crowns should go to a jeweler to avoid water damage or damage to the crown.
- Knowing your watch model and battery type before you start prevents buying the wrong battery and having to open the case twice.
Find your watch model and battery type before you start
The battery size is printed on the old battery itself, but you cannot see it until the case is open. Instead, look up your watch model online or check the paperwork that came with it. Search "[watch brand] [watch model] battery type" — for example, "Timex Weekender battery type." Most watch manufacturers list the battery size on their website or in the manual.
Battery sizes are labeled with numbers like SR626SW, CR2032, or 371. Write down the exact number. When you buy a replacement, the number must match exactly. A battery that is close but not identical may fit loosely, drain faster, or not work at all. Buy from a pharmacy, electronics store, or online retailer — they all stock common watch batteries for $2 to $8.
If you cannot find the model number, take a photo of your watch and bring it to a pharmacy or watch shop. Staff can often identify the battery type by looking at the watch, and you can buy it on the spot without opening the case yourself.
Open the case back without damaging the watch
The case back is the metal disc on the back of the watch. Most watches have either a snap-off back (held by friction) or a screw-off back (held by three to six tiny screws). Check which type yours is by looking at the edge of the case back. If you see small slots or notches around the edge, it is a screw-off. If the edge is smooth, it is a snap-off.
For a snap-off back, insert the flat edge of your case opener into the slot at the edge of the case back. Gently twist or pry upward — do not force it. The back should pop off with light pressure. If it does not move after gentle pressure, try a different slot around the edge. Snap-off backs are designed to open with minimal force, so if you are straining, you are likely in the wrong spot or using the wrong tool.
For a screw-off back, use a small flathead screwdriver that fits the screws snugly. Turn counterclockwise slowly. Watch screws are tiny and strip easily, so use a screwdriver that matches the screw head exactly. Once all screws are out, set them in a small cup or on a piece of tape so you do not lose them. Then gently lift the case back straight up.
Remove the old battery and note how it sits
Once the case back is open, you will see the battery resting in a small compartment, usually held in place by a metal clip or spring. Before you touch anything, take a photo of how the battery sits. The positive side (marked with a + symbol) should face up or down depending on your watch design. When you install the new battery, it must face the same direction.
Use tweezers to gently lift the battery out. If a metal clip is holding it down, lift the clip slightly first, then slide the battery out from underneath. Do not force it. If the battery is stuck, a tiny drop of rubbing alcohol on the tweezers can help it slide out more easily.
Once the battery is out, look at the compartment. If you see any corrosion (white, green, or blue crusty material), wipe it gently with a dry cotton swab. Corrosion can prevent the new battery from making good contact. Do not use water or liquid cleaners — the inside of the watch must stay dry.
Insert the new battery in the same position as the old one
Hold the new battery with tweezers and position it exactly as the old one was positioned. The + side must face the same direction. Slide it under the metal clip or into the compartment until it sits flat and level. If there is a clip, gently press it down over the battery. The battery should not move when you gently shake the watch.
Do not touch the battery with your bare fingers any more than necessary. Oils from your skin can interfere with the electrical contact. If you do touch it, wipe it gently with a clean, dry cloth before installing it.
Once the battery is seated, test the watch by holding it to your ear. You should hear a faint ticking sound. If you hear nothing, the battery may be installed backward or may be defective. Open the case back again and check the polarity, or try a different new battery.
Close the case back and test the watch
For a snap-off back, align the case back with the watch body and press down firmly and evenly around the edge until you hear or feel a click. The back should sit flush with the body with no gaps. Press around the entire edge to make sure it is seated all the way around.
For a screw-off back, align it carefully and insert the screws by hand first to make sure they thread correctly. Then use the screwdriver to tighten them gently in a crisscross pattern (like tightening a car wheel). Do not overtighten — watch screws are fragile and strip easily. They should be snug but not forced.
Once the case is closed, wear the watch for a few hours and check that it is keeping time correctly. If the second hand is moving smoothly and the watch is keeping accurate time, the battery swap is complete. If the watch is not working, open the case back and check that the battery is seated correctly and facing the right direction.
When to take your watch to a jeweler instead
Some watches should not be opened at home. If your watch is water-resistant or waterproof, opening the case back yourself can break the seal and let water inside. Water damage is expensive to repair and may be permanent. If your watch is rated for water resistance (usually marked as "water resistant to 30m" or higher), take it to a jeweler.
Watches with screw-down crowns (the knob you turn to set the time) are also better left to a professional. The crown is delicate and straightforward to damage if you are not used to handling it. Vintage watches, luxury watches, and watches still under warranty should go to a jeweler or authorized service center to avoid voiding the warranty or damaging a valuable piece.
A jeweler will charge $15 to $50 for a battery swap, but that cost is worth it if your watch is sealed, valuable, or still under warranty. Call ahead and ask the price — it varies by shop and by watch type.
Frequently Asked Questions
How do I know if my watch battery is dead or if something else is wrong?
A dead battery is the most common reason a watch stops. If the second hand is not moving at all and the watch has not been worn in weeks, the battery is almost certainly dead. If the second hand is moving but very slowly, or if the watch stops and starts randomly, the battery may be dying. If the watch was working fine and suddenly stopped after you dropped it or got it wet, the problem may not be the battery — take it to a jeweler.
Can I use any battery that fits in the case, or does it have to be the exact model number?
It must be the exact model number. A battery that is close in size may fit loosely and make poor contact, or it may have different voltage and drain much faster. Using the wrong battery can also damage the watch's circuit board. Always match the number exactly.
What should I do if I lose one of the tiny screws from the case back?
Watch screws are standard sizes and can be replaced. Take your watch to a jewelry store or watch repair shop with the remaining screws so they can match the size. A replacement screw costs $1 to $3. Do not try to close the case back with missing screws — the case will not seal properly and water or dust can get inside.
Is it safe to open a watch that is still under warranty?
No. Opening the case back yourself will void most watch warranties. If your watch is still under warranty, contact the manufacturer or an authorized service center for a battery replacement. They will do it for free or at a reduced cost, and your warranty will remain valid.
How long does a new watch battery last?
Most watch batteries last two to five years depending on the watch type, how often you wear it, and the battery size. Larger batteries last longer than smaller ones. Watches you wear every day may drain the battery faster than watches you wear occasionally. When the battery dies, you straightforward repeat this process with a new one.