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

Most Timex watches use a snap-off or screw-off case back that you can open at home without special tools beyond a basic watch case opener (a flat metal pry tool that costs $3 to $8). Once the case is open, you'll remove the old battery, note its size number, drop in a new one of the same size, and snap or screw the case closed again. The whole job takes five to ten minutes.

Some Timex models—particularly older or waterproof watches—have sealed cases that require a jeweler or watch repair shop to open. You'll want to check your specific model first by looking at the case back for waterproof markings or consulting your instruction manual. If you force a sealed case, you can break the gasket and let water damage the movement inside.

Key Takeaways

  • Snap-back and screw-back Timex cases can be opened with an inexpensive watch case opener tool available at drugstores or online.
  • Write down the battery size number (like SR626 or LR626) before you buy a replacement, because Timex watches use different sizes depending on the model.
  • Waterproof and vintage Timex watches often have sealed cases that need professional opening, so check your watch manual or the case back for waterproof markings.
  • Replacement batteries cost $3 to $10 and are sold at drugstores, supermarkets, and online retailers alongside watch tools.

Identify your watch case type before you start

The first step is to look at the back of your watch. Timex makes two main types of case backs: snap-back (smooth, with a slight lip around the edge) and screw-back (has visible screw slots or grooves around the rim). Snap-back cases are more common on everyday Timex watches. Screw-back cases are usually on sport or diving models.

If your watch is marked "waterproof" or "water resistant" with a depth rating (like "50M" or "100M"), it likely has a sealed case that requires professional tools to open safely without damaging the seal. Check the instruction manual that came with your watch, or search online for your specific Timex model number—the manual will tell you whether the case is user-openable.

Get the right tools and battery size

You need three things: a watch case opener (also called a case back remover), the correct replacement battery, and optionally a small plastic tweezers to handle the battery without touching it with your fingers. The case opener is a flat metal tool with a notch or slot at the end; buy one at a drugstore, supermarket pharmacy, or online for $3 to $8. Plastic tweezers cost $2 to $4.

Before you buy a battery, you must know the size. Open the case back (see the next section), look at the old battery, and write down the number printed on it—it will be something like SR626, LR626, SR927, or LR44. These letters and numbers tell the battery maker and size. Take that number with you or search for it online to buy the exact replacement. Batteries cost $3 to $10 depending on the type and where you buy them.

Open a snap-back case

Place your watch face-down on a soft cloth or towel so you don't scratch the crystal. Locate the small notch or groove on the edge of the case back—it's usually at the 6 o'clock position (bottom of the watch). Fit the flat end of your case opener into that notch, making sure it sits flush against the case back.

explore steady, gentle pressure downward and slightly to the side, as if you're prying the case back up. Do not twist or jab—a slow, even pry works better and is less likely to slip and scratch the watch. You should feel the case back start to lift. Once there's a small gap, you can often lift it the rest of the way by hand. If it's stuck, repeat the prying motion at a different point around the edge. The case back should come free without force.

Open a screw-back case

Place your watch face-down on a soft cloth. Look at the case back and identify the screw slots or grooves around the rim. Some Timex screw-backs have a single slot across the center; others have multiple grooves around the edge.

If your case opener has a slot that fits the grooves, insert it and turn counterclockwise (left) slowly. If the grooves are around the edge and your opener has a notch, fit the notch into one of the grooves and turn counterclockwise. explore steady pressure—do not force it, because you can strip the grooves. Once the case back is loose, unscrew it the rest of the way by hand. Set it aside on your cloth so you don't lose it.

Remove the old battery and install the new one

Inside the case, you'll see the battery sitting in a small metal holder or clip. The battery is usually a flat, coin-shaped disc. Use your plastic tweezers or a fingernail to gently lift one edge of the battery and slide it out. Do not touch the flat surfaces of the battery with your bare fingers, because skin oils can reduce its lifespan.

Before you install the new battery, check that it matches the number you wrote down from the old one. Slide the new battery into the holder with the positive side (usually marked with a + or the shiny side) facing up, unless the holder clearly shows otherwise. Press gently until it sits flat and is held by the clip. If the battery doesn't sit flush, remove it and flip it over—you may have had the polarity backward.

Close the case back and test the watch

For a snap-back case, align the case back with the watch body and press down firmly and evenly around the edge until you hear or feel a click. Press all the way around the rim to make sure it's seated properly. For a screw-back case, screw the case back on by hand first, then use your case opener to tighten it snugly—do not over-tighten, because you can strip the threads.

Turn the watch over and check that the second hand is moving. If it is, the battery is installed correctly and the watch is working. If the second hand is not moving, remove the case back, flip the battery over, and try again. Once the watch is running, you're done. Dispose of the old battery at a drugstore, supermarket, or hazardous waste facility—do not throw it in the trash.

When to take your watch to a professional

If your watch case won't open after gentle prying, or if it's marked waterproof, take it to a jeweler or watch repair shop instead of forcing it. Forcing a sealed case can break the gasket and let water inside, ruining the movement. A jeweler can open it, replace the battery, and reseal it with a new gasket for $15 to $30.

If the watch still doesn't run after you install a new battery, the problem is likely not the battery. The movement may need cleaning or repair, which is beyond a battery change. A jeweler can diagnose the issue and tell you whether repair is worth the cost.

Frequently Asked Questions

How do I know which battery size my Timex needs?

Open the case back and look at the old battery. The size is printed on the flat surface—it will be a code like SR626, LR44, or SR927. Write that number down and buy a replacement with the same code. If you can't open the case, search online for your Timex model number and battery size, or call a jeweler with your model number and they can tell you.

Can I use any brand of battery, or does it have to be Timex?

Any brand of battery with the correct size code will work. Timex does not make batteries—they use standard watch batteries from makers like Energizer, Maxell, and Renata. Buy whichever brand is available at your drugstore or online. The price and lifespan are usually the same across brands for the same size code.

What if I drop the battery inside the watch case?

Stop and tilt the watch gently to find it. Do not shake the watch, because the battery can roll into the movement and cause damage. Once you locate it, use plastic tweezers to lift it out. If you cannot reach it, close the case and take the watch to a jeweler—they have tools to retrieve it safely.

How long does a Timex watch battery last?

Most Timex batteries last two to five years depending on the battery type and how often you use the watch. Batteries marked SR (silver oxide) usually last longer than LR (alkaline) batteries. Once the watch stops, the battery is dead and needs replacement.

Do I need to reset my Timex after changing the battery?

No. Once you install the new battery and close the case, the watch will start running again at the time it stopped. You do not need to reset it unless it's a Timex with a digital display or alarm function—check your manual for those models.