What are SR621SW Watch Battery Equivalents?

The SR621SW is one of the most common watch batteries. Its dimension is 6.8 mm × 2.1 mm. You'll find it in wristwatches, small electronics, and precision devices. Sometimes, it is also known as 364.Different brands uses different names and codes to name this battery. 

This can easily confuse many people. So it is important to understanding battery SR621SW equivalents. In this article, we’ll explore what the button battery SR621SW battery is, its specifications, common alternatives, and tips for choosing the right replacement.

The watch battery SR621SW is a compact, silver oxide button cell. This battery has a diameter of 6.8 mm and a height of 2.1 mm. It is one of the most common watch batteries. 

Its chemical properties provides a voltage of 1.55 volts and delivers consistent energy output over time. This make it ideal for analog wristwatches, calculators, medical instruments, and toys. 

Meantimes, its chemical composition offers a high energy density and excellent resistance to leakage. This ensures its reliability and longevity. 

Sometimes, manufatures label this battery as 364, AG621, or SR621. The code “SR621SW” follows the IEC (International Electrotechnical Commission) naming system, where:

Silver Oxide Chemistry: Provides stable voltage output for reliable performance.

Compact Size: 6.8 mm (diameter) × 2.1 mm (height). This makes it ideal for small devices.

Nominal Voltage: Provides a stable 1.55 volts of power.

Low-Drain Design (SW): It is suitable for devices like analog watches that need steady, low power.

Long Shelf Life: The 364 SR621SW has a high energy density. This means it can store a lot of power. It can often last for 2 to 5 years in a watch.

Leak-Resistant: These batteries are sealed very well. This prevents leaks of the chemical inside.

Wide Compatibility: Interchangeable with several equivalent codes (e.g., 364, SR60, D364).

SR621SW (IEC Standard)

This is the official international code. IEC uses it to identify silver oxide, low-drain button cell battery.

The code identifies the battery's dimensions (6.8 mm x 2.1 mm) and chemical composition (silver oxide). When listing battery compatibility, most global manufacturers reference this code as the standard.

364 (Universal Code)

This is the most universal and recognized industry standard code for this battery size. When you see a package labeled "364," it has a diameter of 6.8mm and a height of 2.1mm.

And it uses 1.55V silver oxide chemistry. Meanwhile, it offers stable voltage output, making it ideal for watches and other precision electronics.

Many brands, inlcuding Energizer, Renata, Sony/Murata, and Maxell use this code. When buying a SR621SW battery replacement, you can confidently purchase a 364 battery.

SB-AG / SB-DG (Seiko)

The code often appears in Seiko battery brands. The "SB" often means "Silver Battery," and "AG" refers to the element silver.

This naming convention emphasizes its high-quality silver oxide construction. It provides a stable voltage and long service life. It is a good watch battery SR621SW equivalent.

280-34 (Citizen)

Citizen uses the code 280-34 to refer to equivalent SR621SW batteries. Citizen watch documentation or parts lists often found this number. Even if the product manual does not list the IEC standard code, users can identify the correct battery for their timepieces.

V364 (Varta)

German battery manufacturer Varta labels SR621SW equivalent battery as the V364. The "364" ensures that the battery's dimensions and electrical characteristics exactly match standard specifications.

Known for quality and durability, Varta batteries are popular in Europe and trusted for reliable watch performance. Despite the different label, the specifications are same as the 364.

R621 (Rayovac / General)

Rayovac and some generic brands use alternative code R621 to represent the watch batteries SR621SW. While less common, it is completely interchangeable with other equivalents. Value packs or lower-cost alternatives have this label.

D364

This is the specific model number for Duracell brand battery. The "D" identifies it as a Duracell product. While the "364" means it meets to the standard size.

Duracell's D364 is a trusted silver oxide battery. It is known for its reliability and consistent power output. When you choose D364, you get a high-quality product from a well-known brand.

364W

The standard 364 code with the "W" suffix is a minor variation. Sometimes, some brands use this code. This does not indicate a difference in size, voltage, or chemistry from a standard SR621SW 364 battery.

It is simply an internal name used for a package or product line. A 364W is complete replacement battery for SR621SW.

GP364

This model number refers to the 364-size battery produced by the manufacturer GP (Guangzhou Palm Enterprise) Battery.

GP is a globally recognized brand. Its GP364 cell is a silver oxide battery that meet international standards. It offers the same reliable performance and sizes as the original battery. This is a brand equivalent product with guaranteed compatibility.

K364

Some manufacturers and brands use this code to identify compatible versions of their standard batteries. The "K" may represent a specific product series or brand.

The "364" generally defines its form and function. It uses the same 1.55V silver oxide chemistry and is a direct SR621SW alternative. When you see the K364, you can trust that it’s a good replacement for the 364 SR621SW battery.

SR60, SG1, 164 (Other Labels)

These codes are additional designations from various manufacturers. For example, SR60 is technical identifier. Sometimes, the consumer markets use SG1 and 164. All of these codes have the same dimensions, chemistry, and performance as the 364 battery SR621SW.

AG1

The consumer market widely uses AG1 as a label. Both alkaline and silver oxide versions of the 621 battery typically use this label.

While it has the same dimension as the sony SR621SW, buyers must check whether it is alkaline or silver oxide. For longer-lasting performance, we always recommend the silver oxide version (SR621SW/364).

LR60

LR60 is an alkaline battery and is the same size as the SR621SW sony. However, it has poorer voltage stability and a shorter lifespan than silver oxide batteries. It is generally cheaper and acceptable for devices with lower power demands.

LR621

LR621 is another alkaline version of the same size battery. Like LR60, it is not as durable as the silver oxide 364. But it can still power small devices temporarily. It is more susceptible to voltage drops and is therefore less suitable for use in watches.

SR621

This code has the same functionality as the SR621SW battery nearby. The omission of the "SW" suffix is a common variation among different battery producers.

The "SR" prefix indicates it uses silver oxide chemistry. This chemical composition ensures the same stable voltage output and long lifespan.

It is manufactured to the exact same international standards and specifications. Therefore, an SR621 battery is compatible and is the same product with a slightly different name.

AG621

In this model, the "AG" is a common industry abbreviation. It means silver oxide and is derived from the chemical symbol for silver, Ag. This clearly shows that it has the same electrochemical system as the SR621SW battery sony.

It is designed to the exact dimensions and performance characteristics of a standard 364 battery. This makes the AG621 a direct and reliable replacement for any device requiring the SR621SW.

G621

This is another manufacturer-specific part number. It is a direct equivalence to the battery type SR621SW. The "G" is most likely some company's brand or product line identifier.

The number "621" indicates its size and type. It is a silver oxide battery designed to meet or exceed the original specifications. Consumers can trust that G621 battery will provide the right power and suitability for their device.

L621

Sometimes, this model number can cause confusion. Because alkaline batteries (e.g., LR44) is usually use the "L" prefix. In this specific context, some manufacturers list L621 as a silver oxide equivalent.

Always verify that any battery labeled L621 specifies a silver oxide chemistry to ensure proper performance. And this can avoid the potential issues of using an alkaline cell in a device designed for silver oxide.

Equivalents and Their Brands

Key Points:

Battery equivalents play a crucial role. Because manufacturers often use different codes for the same battery size and chemistry.

Without knowing the equivalents, it can be confusing to find the right replacement, especially when the original code (such as SR621SW) isn’t available in your local store.

Equivalents ensure that users can:

Find Replacements Easily

You might go to a store and they are out of SR621SW batteries. But if you know that a "364" battery is the same thing, you have more options. You can find the right battery faster and more easily.

Avoid Performance Issues

Choosing the wrong type (e.g., alkaline instead of silver oxide) can shorten battery life or cause unstable performance in sensitive devices like watches.

Save Time and Money

Knowing equivalents from different brands can help you compare and choose the most reliable product without wasting money.

Maintain Device Longevity

Using the right equivalent prevents leakage or inconsistent voltage and avoids damage to delicate electronics.

Understanding Compatibility

Your device's manual might list several battery numbers that will work. If you understand that these are all equivalents, you can confidently choose any of them.

SR621SW and SR626SW are both silver oxide watch batteries. However, they differ slightly in size and capacity. Therefore, they are not always interchangeable.

Size

The SR626SW is slightly taller. This means it won't properly fit devices designed for the SR621SW.

Capacity & Lifespan

The SR626SW battery walmart typically has a higher capacity. Because it has greater thickness and a longer runtime in compatible devices.

Applications

Both batteries have similar chemistry and voltage (1.55V). But due to the size difference, they are not direct substitutes. To ensure optimal compatibility and performance, always select the exact same battery type recommended by the manufacturer.

The SR621SW and LR621 are the same size (6.8 mm × 2.1 mm), but they differ in chemistry, performance, and lifespan. Knowing these differences helps ensure you choose the right replacement for your device.

Which one should you use?​

You should always use the battery type recommended by the device manufacturer.

If your device needs an SR621SW, you should use a silver oxide battery (SR621, 364, etc.). Using an alkaline LR621 might cause problems.

Because its voltage drops over time, a device(e.g., a watch) might run slower as the battery gets weak. The higher initial voltage of the silver oxide battery (1.55V vs 1.5V) is also important for some circuits.

While an LR621 might physically fit and work for a short time, it is not the best choice for devices designed for silver oxide power. It may not last very long and may not provide enough power for your device to function properly.

When replacing an SR621SW battery, selecting the correct equivalent. This ensures your device runs smoothly and avoids potential damage. Here are some important tips:

Check the Device Manual or Old Battery

Look for the exact code (e.g., SR621SW, 364, V364). Always start with the manufacturer’s recommendation.

Prefer Silver Oxide Over Alkaline

Especially in watches, choose SR621SW (silver oxide) instead of LR621 (alkaline) for longer life and stable voltage.

Match the Size

Ensure the replacement battery has the same diameter (6.8 mm) and height (2.1 mm) to fit correctly.

Compare Brand Equivalents

Different brands use different codes (e.g., V364 for Varta, 280-34 for Citizen, SB-AG for Seiko). All refer to the same size and chemistry.

Buy from a Reputable Brand

Buy batteries from well-known brands like Energizer, Duracell, Panasonic, Renata, or Sony. This ensures quality and reduces the risk of leaks.

Check Expiry Dates

Even unused batteries lose power over time. Choose fresh stock with the latest manufacturing or expiry date.

Consider Application

For watches and medical tools, always go with silver oxide (SR621SW). If cost is a concern, an alkaline LR621 may be acceptable for toys or calculators.

What you need:​​

Steps:​

The SR621SW is a small and reliable battery. Watches and other compact electronics devices widely use it. Its alternative models, such as 364, SR60, D364, SB-AG/DG and LR621, offer more flexible purchasing options. 

However, for the best performance, it is recommended to use silver oxide versions(e.g., SR621SW or 364) rather than alkaline alternatives. By understanding the differences, checking compatibility, and following safe replacement steps, you can keep your devices running smoothly.

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