A watch that suddenly stops working may simply need a new battery. Replacing a watch battery can be a straightforward task when you have the right tools, the correct replacement battery, and a little patience.

Whether you have a traditional analogue watch, digital watch, or another battery-powered timepiece, knowing how to replace a watch battery can save you time and help you avoid unnecessary replacement costs.

In this guide, we'll explain how to change a watch battery step by step, what tools you need, how to identify the correct replacement battery, and when it's better to have the job done by a professional.

What You Need Before Replacing a Watch Battery

Before opening your watch, gather the following tools and supplies:

• Correct replacement watch battery
• Small watchmaker's screwdriver
• Case-back opening tool
• Plastic tweezers or non-magnetic tweezers
• Small pry tool, if required
• Soft cloth or watchmaker's mat
• Magnifying glass or loupe
• Small container for screws and parts

The most important item is the correct replacement battery. Watch batteries come in many sizes and types, including silver-oxide batteries and lithium coin-cell batteries.

If you're unsure which battery your watch requires, check the number printed on the old battery or consult the watch manufacturer's specifications.

Step 1: Identify the Correct Watch Battery

Before removing anything, determine which battery your watch uses.

Common watch battery numbers include:

• SR521SW
• SR621SW
• SR626SW
• SR920SW
• SR927SW
• SR936SW
• CR2016
• CR2025
• CR2032
• CR2450

Battery numbers can also have equivalent or cross-reference numbers depending on the manufacturer.

For example, a battery marked 364 is commonly associated with SR621SW, while 379 is commonly associated with SR521SW.

However, don't choose a battery based only on appearance. Two batteries can look similar while having different thicknesses, voltages, or electrical characteristics.

Tip: If possible, take a clear photo of the existing battery before removing it. This gives you a useful reference when installing the replacement.

Know More: How to Find the Right Battery for Your Watch: A Complete Guide

Step 2: Prepare Your Workspace

Replacing a watch battery involves handling small components, so choose a clean, well-lit workspace.

Place a soft cloth underneath the watch to protect the crystal and case from scratches.

Keep screws, clips, and other small components in a small container so they don't get lost.

Avoid working over carpet, where tiny watch parts can easily disappear.

Step 3: Determine the Type of Watch Case Back

Watch backs generally fall into three common categories:

Screw-Back Case

A screw-back case has grooves around the edge and is designed to be opened using a suitable case-back wrench or opening tool.

Snap-Back Case

A snap-back case usually has a small notch around the edge. A suitable case knife or case-opening tool can be used to carefully release the back.

Screw-Down Case

Some watches use several small screws to secure the case back. These require a small precision screwdriver.

Important: Don't force the case back open. Using the wrong tool or excessive pressure can scratch the watch or damage the case.

Also Know: How to Remove Watch Case Back: Tools & Tips

Step 4: Carefully Open the Watch

Place the watch face-down on the soft cloth.

If it has screws, remove them carefully and keep them together.

For a snap-back case, locate the opening notch and gently insert the appropriate case-opening tool.

For a screw-back case, use a compatible case-back wrench and turn it carefully.

Once the case back is loose, remove it gently and place it somewhere safe.

Step 5: Locate the Existing Battery

Inside the watch, you should see the battery secured in a small holder or clip.

Before removing it, take note of:

• Battery number
• Battery orientation
• Positive (+) and negative (-) sides
• Position of the retaining clip
• Any small screws or brackets holding the battery

Taking a photograph at this stage can be extremely helpful.

Step 6: Remove the Old Battery

Use plastic tweezers or an appropriate non-magnetic tool to carefully release the battery from its holder.

Do not use excessive force.

Avoid touching other delicate components inside the movement.

If the battery is held in place by a metal clip, gently move the clip according to the design of the holder rather than bending it aggressively.

Once removed, compare the old battery with your replacement to make sure the markings and physical dimensions match.

Step 7: Install the New Watch Battery

Place the new battery into the holder in the same orientation as the original battery.

In many watches, the positive side faces upward, but this isn't universal. Always follow the orientation indicated by the movement or the position of the original battery.

Make sure the battery sits securely in its holder.

Do not force the battery into place.

Step 8: Check Whether the Watch Is Working

Before closing the case, check whether the watch has started operating.

Depending on the type of watch, you may see:

• The second hand begin moving
• The digital display turn on
• The watch hands start moving
• The alarm or other functions become active

If the watch doesn't start, don't immediately assume the new battery is faulty.

Check that:

1. The battery is the correct type.
2. The battery is installed in the correct direction.
3. The battery is properly seated.
4. The retaining clip is positioned correctly.
5. The battery contacts are clean.
6. The watch movement hasn't been damaged.

If the watch still doesn't work, professional inspection may be necessary.

Step 9: Inspect the Case Gasket

Many watches have a small rubber gasket around the case back that helps protect the movement from moisture and dust.

Before closing the watch, inspect the gasket.

Look for:

• Cracks
• Flattening
• Damage
• Dirt
• Incorrect positioning

If the gasket is damaged, it may need to be replaced.

This is particularly important for watches that are designed to offer water resistance.

Know About: How to Remove Watch Links at Home: Step-by-Step Guide

Step 10: Close the Watch Case

Once you've confirmed that the watch is working, carefully reinstall the case back.

For a snap-back case, make sure the gasket is correctly positioned and press the case back into place using appropriate pressure.

For screw-back cases, carefully thread the case back and tighten it using the correct tool.

For screw-secured backs, reinstall each screw carefully without overtightening.

Never assume that replacing the battery restores the watch's original water resistance. If the watch is designed for water resistance, professional resealing and pressure testing may be recommended after opening the case.

Step 11: Set the Time and Date

After replacing the battery, reset the time and date if necessary.

For watches with additional functions, check that everything works correctly, including:

• Date display
• Chronograph functions
• Alarm
• Backlight
• Buttons
• Digital functions

If all functions operate normally, your battery replacement is complete.

How Often Should You Replace a Watch Battery?

The lifespan of a watch battery varies depending on the watch movement, battery type, features, and usage.

Simple analogue watches may operate for a significant period on one battery, while watches with additional functions or frequent backlight and alarm use may consume more power.

Instead of replacing a battery according to a fixed schedule, pay attention to signs that the battery may be running low.

Common signs include:

• The watch stops completely
• The second hand moves irregularly
• A digital display becomes faint
• The watch loses time
• Functions stop working correctly

Some watches have low-battery indicators that provide an additional warning.

How Do I Know Which Watch Battery I Need?

The easiest way is to check the number printed on the existing battery.

You can also check:

• The watch manual
• Manufacturer specifications
• The movement inside the watch
• A battery cross-reference chart
• A watch repair professional

Don't select a replacement solely because it appears to be the same size.

For example, CR2016, CR2025, and CR2032 are all 20 mm in diameter, but they have different thicknesses. Using the wrong battery can cause fitting or performance problems.

Learn About: Watch Battery Cross Reference Chart: Find the Right Battery Replacement

Silver Oxide vs Lithium Watch Batteries

Two common categories of watch batteries are silver oxide and lithium.

Silver Oxide Batteries

Silver oxide batteries are commonly used in traditional watches and are available in many small sizes.

Examples include:

• SR521SW
• SR621SW
• SR626SW
• SR920SW
• SR927SW

Lithium Batteries

Lithium coin-cell batteries are commonly used in digital watches and other electronic devices.

Examples include:

• CR2016
• CR2025
• CR2032
• CR2430
• CR2450

Always use the battery type specified for your watch.

Common Mistakes When Replacing a Watch Battery

Replacing a watch battery is relatively simple for some watches, but mistakes can damage the case or movement.

Avoid these common errors:

1. Installing the Wrong Battery

Similar-looking batteries aren't necessarily interchangeable.

2. Installing the Battery Upside Down

Always check the polarity before installation.

3. Using Excessive Force

Watch components are small and delicate. If something doesn't move easily, stop and check whether you're using the correct tool.

4. Touching the Battery Excessively

Use suitable tweezers and avoid unnecessary contact with the battery and movement.

5. Losing the Case Gasket

A misplaced or damaged gasket can affect the watch's protection against moisture and dust.

6. Scratching the Case

Using an unsuitable screwdriver, knife, or case-opening tool can leave marks on the watch.

7. Assuming Water Resistance Is Unchanged

Opening a water-resistant watch can compromise its sealing. Professional resealing and testing may be required.

When Should You Use a Professional Watch Repairer?

DIY watch battery replacement isn't suitable for every watch.

Consider professional assistance if:

• The watch is expensive or valuable.
• The watch has a complex movement.
• The case back is difficult to open.
• You cannot identify the correct battery.
• The watch is highly water-resistant.
• The battery has leaked.
• The movement appears damaged.
• You don't have the appropriate tools.
• You are uncomfortable working with very small components.

A professional can also inspect the movement, replace damaged gaskets, and perform water-resistance testing where appropriate.

Frequently Asked Questions About Watch Battery Replacement

Q. Can I replace a watch battery myself?

Ans. Yes, some watches can be safely opened and fitted with a new battery at home if you have the correct tools and battery. However, complicated, valuable, or water-resistant watches may be better handled by a professional.

Q. How do I know when my watch battery needs replacing?

Ans. A stopped watch is the most obvious sign. Other signs can include an irregular second hand, a dim digital display, loss of time, or certain functions no longer working.

Q. Can I use any battery that fits my watch?

Ans. No. The replacement battery should match the specifications required by the watch. Physical size alone isn't enough to determine compatibility.

Q. What happens if I put the wrong battery in my watch?

Ans. An incorrect battery may not fit properly or may cause the watch to operate incorrectly. Always verify the battery number and specifications before installation.

Q. Should I replace the gasket when changing a watch battery?

Ans. Not necessarily every time, but the gasket should be inspected. If it is damaged, hardened, flattened, or incorrectly positioned, replacement may be appropriate.

Q. Can I replace a water-resistant watch battery myself?

Ans. You can physically replace the battery in some water-resistant watches, but opening the case can affect its sealing. Professional resealing and pressure testing may be advisable if maintaining water resistance is important.

Q. How can I find a replacement for an old watch battery?

Ans. Start by identifying the number printed on the existing battery. You can then use a watch battery cross-reference chart to find common equivalent numbers and verify the correct size and type.

Final Thoughts

Learning how to replace a watch battery can be useful for anyone who owns a battery-powered watch. With the correct replacement battery, suitable watch tools, and careful handling, many straightforward watch battery replacements can be completed at home.

The most important step is choosing the correct battery. Always check the battery number, type, size, voltage, and polarity before installation.

If you're looking for replacement batteries for different watch models, explore our Watch Batteries collection at Thatwatchshop to find a range of commonly used watch battery sizes and types.

When in doubt—especially with valuable, complex, or water-resistant watches—consider having the battery replaced by a professional watch repairer.