You can replace most Timex watch batteries yourself with a coin and steady hands

A Timex watch battery typically lasts two to three years before the watch stops. You do not need to visit a jeweler or send the watch away—most Timex models have a snap-off case back that you can open with a coin. Inside, you will find a small battery that costs between $3 and $8. The whole job takes about ten minutes if you work slowly and keep track of the tiny parts.

The process is the same whether you own a Timex Weekender, Ironman, or classic analog model: pry off the case back, note which direction the battery faces, swap it for a fresh one, and snap the back on again. The hardest part is not losing the battery or the gasket—a rubber ring that keeps water out—while you work.

Key Takeaways

  • Most Timex watches have a snap-off case back that opens with a coin; a few models are glued shut and require a jeweler.
  • Write down the battery number printed on the old battery before you remove it, so you buy the exact same type at a drugstore or online.
  • The gasket—a thin rubber ring around the case back—must go back in the same position, or water will seep into the watch.
  • If the case back is stuck, warm it gently with a hair dryer or run it under warm water to loosen the plastic, then try again.

What you need before you start

Gather these items on a clean, flat surface before you open the watch. A paper towel or small cloth keeps the battery and gasket from rolling away. A coin—a dime or penny works—is your only tool; the edge fits into the slot on the case back.

Buy the replacement battery before you open the watch. Look at the old battery number (printed on its flat side) and search for that exact model online or at a drugstore pharmacy counter. Common Timex batteries are SR626SW, SR927SW, and 395. If you cannot read the number, you can open the watch first and look at the battery itself, but it is easier to know what you are buying ahead of time.

Work in good light. A desk lamp or phone flashlight pointed at the watch helps you see the tiny battery and gasket. If your eyesight is not sharp, a magnifying glass or jeweler's loupe makes the job much easier.

How to open the case back

Hold the watch face-down in your non-dominant hand. Look at the back of the watch for a thin slot that runs around the edge—this is where the coin goes. The slot is usually on the very rim of the case back, not in the center.

Insert the coin edge into the slot and turn it counterclockwise, as if you were opening a jar. Turn slowly and steadily; do not force it. If the case back does not budge after a few gentle turns, stop. Warm the watch under warm running water or with a hair dryer on low heat for 30 seconds, then try again. Plastic case backs sometimes stick when they are cold.

Once the case back loosens, you can usually unscrew it by hand. Set it down on your cloth or paper towel with the gasket still attached—do not pull the gasket off yet. The gasket should stay in the groove on the case back until you are ready to put everything back together.

Removing and replacing the battery

Look inside the watch. You will see the battery sitting flat in a small compartment, usually held in place by a metal clip or spring. The flat side of the battery faces up. Write down or photograph the battery number before you touch it.

Gently lift the edge of the battery with your fingernail or the edge of the coin. The metal clip or spring will release, and the battery will come free. Do not touch the flat sides of the new battery with your bare fingers—skin oils can reduce its lifespan. Hold it by the edges only.

Place the new battery into the compartment with the flat side facing up, in the same direction as the old one. The metal clip or spring should snap back over the edge automatically. If it does not, gently press it down until it holds the battery in place. The battery should not move when you tilt the watch.

Putting the case back on and testing

Before you close the watch, check that the gasket is still in the groove on the case back. It should sit flat all the way around the rim. If it has shifted, gently press it back into place with your fingernail. A misaligned gasket will let water into the watch.

Align the case back with the watch body. You will see a small notch or mark on both the case back and the watch body—line these up so the back goes on straight. Press the case back down gently and turn it clockwise with your coin until it is snug. Do not over-tighten; you are aiming for snug, not as tight as possible.

Turn the watch over and press the crown (the knob on the side) to make sure the watch is working. You should hear a faint ticking or see the second hand move. If nothing happens, open the case back again and check that the battery is sitting flat and the metal clip is holding it down.

Common mistakes that stop the watch from working

The most frequent error is installing the battery upside down. The flat side must face up toward the back of the watch. If the watch does not tick after you close it, open the case back and flip the battery over.

The second mistake is forgetting the gasket or putting it back crooked. The gasket is a thin rubber ring that sits in a groove on the case back. If it is missing or misaligned, water will eventually seep in and damage the watch. Before you close the case back, always check that the gasket is seated flat all the way around.

Touching the flat sides of the new battery with your fingers can shorten its life, though it will usually still work. If you do touch it, wipe it gently on a clean, dry cloth before you install it.

Over-tightening the case back can crack the plastic or damage the gasket. Tighten until the back is snug, then stop. If you feel strong resistance, you have tightened enough.

When to take your watch to a jeweler instead

A few older Timex models and some specialty watches have case backs that are glued or welded shut. If you cannot find a slot for a coin, or if the back does not budge after gentle warming and turning, the watch is glued. Do not force it—you will crack the plastic. A jeweler or watch repair shop can open it with a case opener tool, usually for $10 to $20 plus the cost of the battery.

If your watch is water-resistant or a diving model, the gasket is especially important. If you are not confident about seating it correctly, a jeweler can do the job and test the water seal afterward. The cost is usually $15 to $30, which is reasonable insurance if the watch is valuable to you.

Frequently Asked Questions

How long does a Timex watch battery last?

Most Timex batteries last two to three years with normal daily wear. Batteries in watches you wear constantly may last closer to two years, while batteries in watches you wear occasionally may stretch to three or four years. The battery will straightforward stop, and the watch will not tick or display the time.

Can I use any battery, or does it have to be the exact Timex model?

You must use the exact battery number printed on the old battery. Different battery types have different voltages and sizes, and using the wrong one can damage the watch or not work at all. A SR626SW is not the same as a SR927SW, even though they look similar. Check the number on the old battery and buy that exact type.

What if I lose the gasket while the case back is open?

If the gasket falls out and you cannot find it, you can order a replacement gasket online for $2 to $5 by searching for your watch model number plus "gasket." Without a gasket, water will eventually seep into the watch and damage it. Do not close the case back without one.

Is it safe to open a water-resistant Timex myself?

You can open it, but the water seal depends on the gasket being seated perfectly. If you are not confident about getting it right, a jeweler can open it, replace the battery, and test the seal for $15 to $30. If you do it yourself, the watch may still be water-resistant, but you have no way to verify it.

What should I do with the old battery?

Take the old battery to a drugstore, electronics store, or recycling center. Many pharmacies have a battery recycling bin near the checkout. Do not throw it in the trash—batteries contain materials that should be recycled. Most places take old watch batteries for free.