What You Need Before You Start

Replacing a watch battery yourself requires three things: the correct replacement battery, a small tool to open the case back, and a clean, well-lit workspace. You can buy replacement batteries at drugstores, supermarkets, and online retailers for $3 to $15 depending on the battery type. The tool—called a case opener or case back remover—costs $5 to $20 and looks like a small flathead screwdriver with a notch or fork at the end. A jeweler's screwdriver set ($8 to $15) works if your watch has screws holding the case back instead of a snap-fit design.

Before you buy anything, you need to know which battery your watch uses. Look inside the case back (the metal or plastic disc on the back of the watch) for a number printed or stamped there—something like SR626, LR44, or 371. That number is your battery type. If you cannot read it clearly, take a photo with your phone's flashlight and zoom in, or search online for your watch brand and model number plus "battery type." Write down the exact number so you do not buy the wrong one.

Key Takeaways

  • Find your battery type by looking at the number stamped inside the case back, then buy that exact replacement at a drugstore or online.
  • Use a case opener tool (not a regular screwdriver) to pry off the case back without scratching or cracking the watch.
  • Note which side of the old battery faces up before you remove it, then install the new battery the same way.
  • Close the case back by pressing firmly and evenly around the edges until you hear or feel a click, then test that the watch runs.
  • If the watch does not start after you install the new battery, the problem is usually a dirty contact or an incorrect battery type.

Opening the Case Back Without Damage

The case back is either snap-fit (held in by pressure) or screw-down (held by one or more small screws). Look at the back of your watch. If you see a thin seam all the way around with no visible screws, it is snap-fit. If you see one or more small screws, use a jeweler's screwdriver to remove them first, then proceed to the next step.

For a snap-fit case back, position your case opener tool into the small notch or slot on the edge of the case back. You will usually find this notch at the 6 o'clock position (bottom of the watch). Gently twist the tool counterclockwise—do not force it. The case back should pop up slightly. Once you feel it loosen, use your fingernail or the tool to pry it the rest of the way off. If it does not budge after gentle twisting, try the notch at a different position (3 o'clock or 9 o'clock) because some watches have multiple notches.

Set the case back down on a clean cloth where you can see it. Do not set it on a sink or table edge where it can roll away and get lost.

Removing and Replacing the Old Battery

Inside the case, you will see the battery sitting in a small metal holder or compartment. Before you touch it, look at which side is facing up—the flat side or the side with a raised bump. Take a photo or write down "flat side up" or "bump side up" so you remember. This matters because batteries only work one direction.

Use a plastic spoon, plastic tweezers, or the edge of your case opener tool to gently pry the old battery out of its holder. Do not use a metal tool directly on the battery because you can create a short circuit. Once the battery is out, look at the metal contacts inside the holder—the small metal pieces the battery sits against. If they look dark, dirty, or corroded, wipe them gently with a clean, dry cloth or a cotton swab. Dirty contacts are the most common reason a new battery does not work.

Place the new battery into the holder with the same side facing up as the old one. Press it down gently until it sits flat and makes contact with the metal pieces. You should feel a slight resistance. Do not force it—if it does not sit flat, you may have the wrong battery type or the battery may be upside down.

Closing the Case Back and Testing

Pick up the case back and line it up with the watch body. For a snap-fit case, press down firmly and evenly around the entire edge until you hear a small click or feel the case back settle into place. You may need to press in several spots—start at the top, then the sides, then the bottom. The case back should sit flush with no gaps. If it does not click or sit flush, remove it and check that the battery is installed correctly and the contacts are clean.

If your watch has screws, replace them now using your jeweler's screwdriver. Tighten them snugly but not so hard that you strip the threads—you should feel mild resistance, then stop.

Once the case is closed, move the watch to your ear and listen for a ticking sound, or look at the second hand to see if it is moving. If the watch starts, you are done. If it does not start after 10 seconds, remove the case back again and check that the battery is seated properly and the contacts are clean. If the watch still does not start, the battery type may be wrong—go back to the number on the case back and verify you bought the correct one.

Common Mistakes That Stop the Watch From Running

The battery is installed upside down. This is the single most common error. Before you close the case, double-check that the flat or raised side matches what you noted from the old battery.

The contacts are dirty. Even a thin layer of dust or corrosion blocks the electrical connection. Wipe the metal contacts with a clean, dry cloth before you install the new battery. If they look dark or crusty, use a cotton swab dampened with a tiny amount of rubbing alcohol, then dry thoroughly.

You bought the wrong battery type. The number on the case back is specific—SR626 is not the same as SR627, and LR44 is not the same as SR44. If you are unsure, take a photo of the number and show it to the store clerk or search online for the exact match.

The case back is not sealed properly. If you close it and it does not click or sits with a visible gap, moisture can get inside and corrode the contacts. Remove it and try again, pressing more firmly around the edges.

When to Take Your Watch to a Professional

If you have tried replacing the battery twice with the correct type, cleaned the contacts, and the watch still does not run, the problem is likely inside the watch movement itself—a broken gear, a damaged spring, or a short circuit. A watch repair shop can diagnose this for $20 to $50 and repair it for $50 to $150 depending on the damage. This is worth doing for a watch you wear regularly or that has sentimental value.

If your watch is waterproof or water-resistant, opening it yourself can break the seal. Some watches have a gasket (a rubber ring) that keeps water out, and removing the case back can damage it. If your watch is rated for water resistance and you are not comfortable with the process, a jeweler or watch repair shop can replace the battery and re-seal it for $15 to $40.

Frequently Asked Questions

Can I use any battery with the same number, or does the brand matter?

The number is what matters, not the brand. SR626 from one maker works the same as SR626 from another. Buy whatever is cheapest and available. Some people prefer name brands like Energizer or Duracell for peace of mind, but generic batteries work just as well and cost less.

What do I do with the old battery?

Watch batteries contain mercury or other metals and should not go in the trash. Take them to a battery recycling program—most drugstores and supermarkets have a collection bin near the checkout, or search online for "battery recycling near me" to find a drop-off location.

How long does a replacement battery last?

Most watch batteries last two to five years depending on the watch type and how often you wear it. Quartz watches (the most common kind) use very little power. Watches with a second hand that ticks every second use batteries faster than ones where the second hand moves smoothly. When the battery dies, you straightforward replace it again using the same steps.

My watch has a crown (the knob on the side) that screws down—does that affect battery replacement?

No. A screw-down crown keeps water out but does not affect how you open the case back. Follow the same steps to remove the case back, replace the battery, and close it again. The crown stays in place the whole time.

Is it safe to replace the battery myself, or should I always go to a jeweler?

It is safe if you follow the steps carefully and use the right tools. The main risks are scratching the watch case (cosmetic only) or installing the battery upside down (straightforward to fix). A jeweler will do it faster and can handle waterproof watches, but for a standard quartz watch, you can do it at home and save $10 to $30.