Watch Battery Dimensions Chart: Sizes, Voltages, and Equivalents Explained

Watch batteries look similar, but they are not interchangeable. Small size or voltage differences can cause poor performance or damage.

To choose the right battery, check six key factors: code, diameter, height, voltage, chemistry, and drain type. This guide explains each and includes a practical watch battery size chart.

Key takeaways

• Watch battery size is listed as diameter × height (mm).
• The battery code on the old cell is the most reliable reference.
• Silver oxide: 1.55V. Alkaline: 1.5V. Lithium coin: 3V.
• Same size does not mean same performance.
• SR626SW (377) is a very common analog watch battery.
• Digital watches often use CR2016, CR2025, or CR2032.
• Smartwatches use rechargeable lithium batteries.

Part 1. What is a watch battery?

A watch battery is a compact power source designed for a watch movement or electronic display. Most traditional watch batteries are round primary cells. This means they are used once and should not be recharged.

Common watch battery types include:

• Silver oxide batteries: Stable 1.55V output for analog quartz watches.
• Alkaline batteries: Lower-cost 1.5V cells used in some basic watches and small devices.
• Lithium coin batteries: 3V cells used in many digital watches, alarms, timers, and electronic modules.
• Rechargeable lithium batteries: Custom lithium-ion or lithium polymer cells used in smartwatches and fitness trackers.

The terms “button cell” and “coin cell” are often used together. A button cell is usually small and thick relative to its diameter. A coin cell is normally wider and flatter. Both formats can be found in watches.

For a closer comparison of 1.55V, 3V, and rechargeable systems, see our guide to watch battery voltage.

Part 2. Are all watch batteries the same?

No. Watch batteries differ in size, voltage, chemistry, capacity, and discharge behavior.

Two cells can have the same diameter but different heights. For example, CR2016, CR2025, and CR2032 batteries are all 20 mm in diameter. Their heights are 1.6 mm, 2.5 mm, and 3.2 mm. They cannot be exchanged unless the battery compartment and electrical contacts were designed for the different height.

Two cells can also have the same physical size but different chemistry. LR44 and SR44 batteries both measure about 11.6 × 5.4 mm. However, LR44 is alkaline and provides about 1.5V. SR44 is silver oxide and provides about 1.55V with a flatter discharge curve.

For reliable operation, match the full battery specification rather than only the visible shape.

Part 3. Why do watch battery sizes vary?

Watch manufacturers select a battery around the available space and the power needs of the movement. There is no universal wrist watch battery size.

The required size depends on:

• The thickness and diameter of the watch case
• The space occupied by the movement
• Analog, digital, chronograph, or hybrid functions
• Backlights, alarms, sensors, and wireless features
• Required operating life
• Battery chemistry and nominal voltage
• Peak current and average current demand

A basic two-hand quartz watch has a very low and steady load. A digital watch with a light and alarm has higher pulse-current needs. A smartwatch with Bluetooth and health sensors requires a rechargeable battery system.

Part 4. How to find watch battery size

The best way to find a watch battery size is to identify the battery code already installed in the watch. Do not choose a replacement based only on appearance.

1. Read the code on the old battery

Look for a code such as:

• 377 or SR626SW
• 364 or SR621SW
• 371 or SR920SW
• 395 or SR927SW
• CR2016
• CR2025
• CR2032

The same standardized battery may carry different brand codes. Use a reliable cross-reference chart before buying a replacement.

2. Check the watch manual or movement number

The watch manual may list the required battery. For older watches, search using the movement number rather than only the watch model. The movement number is often printed on the movement or inside the case back.

3. Measure the old battery

When the battery code is missing or unreadable, use a digital caliper.

1. Measure the diameter across the widest part of the battery.
2. Measure the total height from the bottom surface to the top terminal.
3. Record both measurements in millimeters.
4. Compare the values with a watch battery dimensions chart.

A few tenths of a millimeter can affect fit and contact pressure. Do not rely on a ruler or visual estimate.

4. Confirm voltage and chemistry

Dimensions alone are not enough. Confirm whether the watch requires 1.55V silver oxide, 1.5V alkaline, 3V lithium, or a rechargeable battery.

5. Check the drain rating

Silver oxide watch batteries may have an “SW” or “W” suffix:

• SW: Designed mainly for low and steady loads, such as basic analog watches.
• W: Designed for higher pulse loads, such as alarms, lights, or chronographs.

Some modern replacement batteries support a wider load range. Even so, the original watch specification should remain the main reference.

Part 5. Watch battery size chart: common silver oxide cells

The following watch battery sizes chart lists common silver oxide models. Dimensions are nominal. Small differences may appear between manufacturers because of permitted tolerances.

The 377/SR626SW is one of the most common watch battery sizes for small analog quartz watches. The 364/SR621SW and 371/SR920SW are also widely used. However, the correct battery always depends on the movement.

Part 6. Watch battery dimensions chart: alkaline and lithium cells

Some watches use alkaline button batteries or 3V lithium coin cells. The table below covers common sizes.

For more sizes and naming details, see our guides to coin battery sizes, button battery sizes, and CR battery sizes.

Part 7. How to read watch battery codes

Watch battery codes describe the chemistry, shape, and size of the cell. Primary watch battery dimensions and designations are covered by the IEC 60086-3 watch battery standard.

SR626SW code example

• S: Silver oxide chemistry
• R: Round cell
• 6: IEC diameter class corresponding to about 6.8 mm
• 26: Height of about 2.6 mm
• SW: Low-drain watch application

SR626SW is commonly sold as a 377 battery. The same physical size is also available as SR626W or 376 for higher-drain applications.

CR2032 code example

• C: Lithium manganese dioxide chemistry
• R: Round cell
• 20: Diameter of 20 mm
• 32: Height of 3.2 mm

This pattern also applies to CR2016 and CR2025. All three have a 20 mm diameter, but their heights are different.

Part 8. Watch battery equivalents: what does “equivalent” mean?

An equivalent battery should match the required dimensions, voltage, chemistry, and load performance. The word “equivalent” is often used too loosely in online charts.

Brand equivalents

Different manufacturers may use different product numbers for the same standardized cell. For example, SR626SW may appear as 377, D377, V377, or another manufacturer code.

A manufacturer cross-reference, such as the Maxell battery replacement guide, can help compare brand numbers.

Physical equivalents

Some batteries share the same dimensions but do not have the same chemistry. LR44 and SR44 are a common example. Both fit the same physical space, but they have different voltage behavior and operating life.

Drain-type equivalents

Cells such as 377 and 376 share the same size and chemistry. However, 377/SR626SW is associated with lower-drain use, while 376/SR626W is associated with higher-drain use.

Other common low-drain and high-drain pairs include:

Do not assume that two codes are fully interchangeable because they appear in the same replacement list. Confirm the watch manufacturer’s requirement.

Part 9. Silver oxide vs. alkaline vs. lithium watch batteries

Silver oxide is often preferred in traditional quartz watches because its output remains stable for much of the discharge period. Alkaline batteries can fit some of the same compartments, but their voltage drops more gradually during use.

A 3V lithium coin cell must never replace a 1.55V silver oxide or 1.5V alkaline cell unless the watch was designed for it.

Part 10. Watch battery selection by watch type

Part 11. What is the correct pocket watch battery size?

There is no standard pocket watch battery size. Traditional mechanical pocket watches do not use a battery. Quartz pocket watches may use a silver oxide, alkaline, or lithium cell, depending on the movement.

Common analog quartz pocket watch movements may use cells such as 377, 364, 371, or another small silver oxide model. Larger digital or novelty pocket watches may use a CR-series lithium coin cell.

To find the correct pocket watch battery size:

1. Open the case using the correct watch tool.
2. Read the number printed on the old battery.
3. Check the movement number when the battery is missing.
4. Confirm the required voltage and dimensions.

Do not assume that a large watch case requires a large battery. Much of the internal space may be occupied by the movement and case structure.

Part 12. Special cases: solar watches and smartwatches

Solar and kinetic watches

Many solar and kinetic watches use a rechargeable secondary cell. It may look like a standard button battery, but it is not a normal disposable watch battery.

Use the exact manufacturer part. Installing a primary silver oxide or lithium coin cell can prevent charging and may damage the watch.

Smartwatches and connected wearables

Smartwatches normally use a rechargeable lithium polymer battery. These batteries may be flat, curved, round, or custom-shaped. Selection depends on more than diameter and height.

Smartwatch designers must consider:

• Available internal length, width, and thickness
• Required capacity and daily runtime
• Peak current during wireless communication
• Charging voltage and charging rate
• PCM and temperature protection
• Wire, connector, and polarity
• Cycle life and swelling allowance

OEM developers can learn more about wearable device battery solutions. Ufine also supports custom lithium battery development for smartwatches, fitness trackers, smart rings, and other compact devices.

Part 13. How to replace a watch battery safely

1. Confirm the replacement code before removing the old cell.
2. Record which side faces upward.
3. Use suitable watch tools and avoid damaging the gasket.
4. Do not short the positive and negative surfaces with metal tools.
5. Check the contacts for dirt or corrosion.
6. Install the battery without forcing it into the holder.
7. Replace or inspect the case gasket before closing a water-resistant watch.

A thicker battery should not be forced into the compartment. It can bend the retaining clip, damage the movement, or place pressure on the case back.

Water resistance may need professional testing after the case has been opened. For valuable, sealed, or high-water-resistance watches, use an authorized service center.

Part 14. Buying and storing replacement watch batteries

Buy replacement batteries from an established watch service provider, electronics distributor, or battery specialist. Check that the packaging is sealed and the battery has no marks, swelling, leakage, or corrosion.

Store unused batteries in their original packaging. Keep them in a cool, dry location. Do not store loose cells together because their terminals can contact each other or metal objects.

Keep all button and coin batteries away from children. A swallowed battery is a medical emergency. See the U.S. Consumer Product Safety Commission button battery guidance for safety information.

Part 15. How to dispose of old watch batteries

Do not recharge, crush, burn, or open a disposable watch battery. Place non-conductive tape over the terminals after removal and keep the cell away from children.

Disposal rules vary by location. Use a battery collection center, household hazardous waste program, or participating electronics retailer. In the United States, the EPA household battery guidance advises against placing button cells, coin cells, or single-use lithium batteries in household trash or municipal recycling bins.

Part 16. FAQs about watch battery sizes