Opening the case back is the first step, and it determines everything that follows

Most pocket watches use one of three case-back designs: a screw-off back, a snap-off back, or a hinged back. The type you have dictates whether you can do this yourself or need a watchmaker. Screw-off backs require a case opener tool and steady hands. Snap-off backs need a flat tool wedged into a slot and gentle prying. Hinged backs have a small stem you lift or press to open. If you cannot identify which type yours is, or if the back is stuck or corroded, a watchmaker can open it for $15 to $40 and replace the battery at the same time.

Before you open anything, note the battery type currently inside. Most pocket watches use a silver-oxide or alkaline button cell—typically a 357, 364, 371, 377, 390, or 395. The number is printed on the battery itself. If you cannot see it without opening the case, a watchmaker or jeweler can tell you over the phone if you describe the watch model.

Key Takeaways

  • Pocket watch case backs come in three types—screw-off, snap-off, or hinged—and you must identify yours before attempting to open it.
  • The battery type is printed on the old battery itself, and you need this number to buy the correct replacement.
  • A case opener tool costs $8 to $20 and is necessary for screw-off backs; snap-off backs need only a flat tool like a butter knife.
  • If the case back is stuck, corroded, or you are unsure of the design, a watchmaker can open it and install the new battery for $30 to $60 total.
  • Silver-oxide batteries last longer than alkaline ones in pocket watches and are worth the slightly higher cost.

Identifying and gathering the tools you need

For a screw-off back, you need a case opener tool—a small metal device with a handle and two or three prongs that grip the grooves around the case back. These cost $8 to $20 online or at jewelry supply stores. Do not use a screwdriver or pliers; they will slip and scratch the case. If you do not have the tool and do not want to buy one, this is the moment to stop and take the watch to a watchmaker.

For a snap-off back, you need only a flat tool: a butter knife, a flathead screwdriver, or a plastic pry tool. Wrap the flat edge in a thin cloth to avoid scratching the case. For a hinged back, you need nothing—just your fingernail or a soft tool to gently lift or press the stem.

Once you have the tool, gather the new battery (in the correct size), a small bowl or cup to hold screws or small parts, and a clean, well-lit workspace. Pocket watch internals are tiny; losing a part on a dark table is straightforward.

Opening a screw-off case back safely

Place the watch face-down on a soft cloth so the crystal does not get scratched. Position the case opener tool so its prongs fit into the grooves around the case back—there are usually two or three grooves evenly spaced. Press down gently and turn counterclockwise, the same direction you turn a regular screw to loosen it. Do not force it; if it does not budge after a few gentle turns, the back may be stuck from corrosion or old sealant. Stop and take it to a watchmaker rather than risk cracking the case.

Once the back is loose, unscrew it by hand and set it aside. You will now see the battery, usually held in a small metal clip or sitting in a shallow recess. Note how it sits before you remove it—the positive side (marked with a + or flat side) should face up or down depending on the watch design. Take a photo with your phone if you are unsure.

Opening a snap-off case back safely

Look for a small slot or lip around the edge of the case back, usually at the 6 o'clock position (bottom of the watch). Insert your flat tool gently into the slot and explore steady, even pressure to pry the back up. Do not twist or lever hard; snap-off backs are designed to release with moderate pressure. If it does not budge, try a different spot along the edge—sometimes the slot is not where you expect it.

Once the back pops free, lift it away carefully. Again, note the battery orientation before you touch it. Some snap-off watches have a small gasket or rubber seal around the back; if it comes loose, keep it safe and reinstall it when you close the watch.

Removing the old battery and installing the new one

Most pocket watch batteries sit in a metal clip that holds them snugly. Gently lift one edge of the clip with a fingernail or a plastic tool and slide the old battery out. Do not use metal tools that could slip and scratch the movement inside. If the battery is stuck, a tiny dab of rubbing alcohol on the clip can help loosen it; let it sit for a minute, then try again.

Before you insert the new battery, check its orientation against the photo you took or the position of the old battery. Slide the new battery under the clip, positive side facing the correct direction, and press down gently until the clip holds it snugly. The battery should not move if you tilt the watch slightly. If it does, the clip is not seated properly; lift it and try again.

Closing the case back and testing the watch

For a screw-off back, align the grooves on the back with the grooves on the case, then use your case opener tool to turn clockwise until it is snug. Do not over-tighten; you will feel resistance when the seal is tight enough. For a snap-off back, align the back with the case and press down firmly all around the edge until you hear or feel a click. If there is a gasket, make sure it is seated in the groove before you close the back.

Once the back is closed, turn the watch over and check that the hands move when you wind it or shake it gently. If the watch has a second hand, listen for a steady ticking sound. If nothing happens, open the case back again and check that the battery is seated correctly and facing the right direction. If the watch still does not work after a second attempt, the movement may have a problem unrelated to the battery; take it to a watchmaker for diagnosis.

When to take your pocket watch to a professional

A watchmaker is the right choice if the case back is stuck, corroded, or you cannot identify the design. It is also the right choice if you open the watch and find the battery is soldered in place rather than clipped—some older or high-end pocket watches have batteries that require a soldering iron to replace. A watchmaker can also clean the movement and gasket while the case is open, which extends the life of the watch and prevents moisture from getting inside.

The cost of professional battery replacement is usually $30 to $60, including opening and closing the case. This is worth paying if you are unsure of your ability to do it without damaging the watch, or if the case back is difficult to open. A scratched or cracked case is expensive to repair.

Frequently Asked Questions

How often do pocket watch batteries need to be replaced?

Silver-oxide batteries typically last two to three years in a pocket watch. Alkaline batteries last about one year. The exact lifespan depends on how often you wind or shake the watch and the power draw of the movement. If your watch stops suddenly, the battery is likely dead.

Can I use any button cell battery, or does it have to be the exact size?

It must be the exact size—the number on the battery (357, 364, 377, etc.) is not interchangeable. Using the wrong size can cause the battery to rattle loose, not make contact, or not fit in the clip at all. Check the old battery or ask a jeweler before you buy.

What if I drop the battery or the tiny clip inside the watch?

If you drop the battery, pick it up and inspect it for damage before installing it. If you drop the clip or any other small part, use a flashlight and a magnet to locate it inside the case. If you cannot find it or if it is damaged, stop and take the watch to a watchmaker; reassembling it without all the parts will cause problems.

Do I need to seal the case back with anything after I close it?

No. Pocket watch case backs are designed to seal themselves when closed properly. If your watch has a gasket (a thin rubber ring), make sure it is in place before you close the back. Do not use glue or sealant unless a watchmaker tells you to.

My pocket watch is very old—should I replace the battery myself or take it to a professional?

If the watch is an antique or has sentimental value, take it to a professional. Older watches often have delicate movements, corroded cases, or unusual battery configurations. A watchmaker can assess the condition and handle the battery replacement without risking damage to the watch.