364, AG1, LR621, SR621SW Battery Equivalents, and Replacements

LR621 and SR621SW are very popular coin/button cell batteries often used in wrist watches, small toys, calculators, remote keys, and similar small and compact devices.

LR/SR621 batteries are manufactured by many leading brands and can be easily found at online shops and stores.

Updated: January 11, 2022.

LR621 and SR621 Batteries Features and Specifications

LR621 and SR621 batteries are non-rechargeable button/coin cell batteries featuring physical dimensions of 6.8 mm in diameter and 2.1 mm in height. They are commonly available as alkaline and as silver-oxide batteries.

Alkaline batteries are labeled as LR621, LR60, or AG1 batteries. Their nominal voltage is 1.5 volts, but as the battery is used, the voltage drops quickly. Cut off voltage is considered to be 0.9 volts, but if these batteries are used for electronic devices, it is possible that the device has its 'own' cut off voltage, for example, 1.1 or 1.2 volts - when the battery reaches this voltage, the device will either shut-off or starts to behave erratically.

The nominal capacity of LR621/LR60/AG1 batteries is around 12-15 mAh when being discharged down to 0.9 volts. Generally, LR621/LR60/AG1 batteries are used for toys, flashlights, and similar devices where constant voltage is not of ultimate importance.

Silver-oxide batteries are commonly labeled as SR621, SR621SW, SR60, 164, 364, SG1, or even AG1.

The nominal voltage of silver-oxide batteries is 1.55 volts and the cut-off voltage is 1.2 volts. When the battery is in use, voltage drops slightly and stays constant during use. As the battery gets fully discharged, voltage drops off sharply and below 1.2 volts, the battery is considered as being fully discharged.

The nominal capacity of SR621, SR621SW, SR60, 164, 364, SG1 batteries is in the 18-23(25) mAh range.

When compared with alkaline batteries, SR621SW batteries, like all coin cell batteries have a larger capacity, more stable/constant operating voltage, higher cut-off voltage, longer shelf life, and are slightly more expensive.

SR621SW Batteries Cross Reference Chart

The following cross reference chart lists some of the most popular  SR621SW, LR621, 364/363, AG1 battery models, with their most important features and specifications:

As one can see, actual performances vary depending on the discharge current/battery load and temperature but also depending on the battery age.

SR621, SR621SW, SR60, 164, 364, SG1 equivalent silver-oxide batteries are generally used in electronic devices like wrist watches, remote control devices, remote keys, and similar. Although they are not as cheap as alkaline batteries, the price difference is almost negligible - the use of SR621SW or equivalent silver-oxide batteries is recommended even in kids' toys and similar 'electric' devices.

364, AG1, LR621, SR621SW Batteries Frequently Asked Questions (FAQ)

Here are some of the most common Frequently Asked Questions (FAQ) about 364, AG1, LR621, SR621SW, and other similar batteries:

What battery replaces SR621SW? What watch battery is equivalent to SR621SW?

SR621SW battery is a 1.55V silver-oxide battery featuring physical dimensions of 6.8 x 2.1 mm - any sliver-oxide 1.55V 6.8 x 2.1 mm battery from the reputable brands usually labeled as SR621, SR621W, SR60, 164, 364, SG1, etc. can replace SR621SW in most of the operations.

Also, in emergencies, an alkaline 1.5V 6.8 x 2.1 mm battery can be used to replace the silver-oxide SR621SW battery, but with reduced battery life and possible issues due to the not-so-stable output voltage.

Is 377 battery the same as SR621SW?

No, 377 battery is silver-oxide 6.8 x2.6 mm coin cell battery, while the SR621SW battery is silver-oxide 6.8 x 2.1 mm battery.

What size is the SR621SW battery?

SR621SW battery is a silver-oxide 6.8 x 2.1 mm battery.

Are 377 and 364 batteries interchangeable? Can I use a 364 battery instead of 377?

No, despite they feature the same chemistry (silver-oxide) and very similar dimensions:

- 364: 6.8 x 2.1 mm,

- 377: 6.8 x 2.6 mm.

Due to the same diameter and very similar height, it is possible to place 364 battery into the 377 battery compartment, and sometimes even vice versa.

But, if 364 battery is placed in the 377 battery compartment, contact issues may prevent reliable operation. Also, 364 battery features smaller capacity when compared with 377 battery.

If 377 battery is placed in the battery compartment intended for 364 battery, due to the height differences, there may be some physical damage to the device due to the increased height.

What battery is equivalent to 364?

Any silver-oxide 6.8 x 2.1 mm battery, including SR621, SR621SW, SR60, 164, SG1, etc. batteries from reputable brands.

SR621SW, LR621, 364/363 Batteries Safety Issues

SR621SW, LR621, 364/363 batteries are small and shiny objects that can attract kids and pets - that is why most brands pack them in 'pets-safe' or 'kids-safe' packages.

Although modern SR621SW, LR621, 364/363 batteries don't contain pollutants like mercury or cadmium, when swallowed they can cause chemical burns due to the electrolytic processes - these chemical burns are not as dangerous as when larger batteries with higher capacity and even voltage are swallowed, but nonetheless, IF they get swallowed, immediately contact the nearest emergency center and act according to their instructions.

Better safe than sorry...

Long Story Short: if you need good LR621, LR60, AG1, SR621, SR621SW, SR60, 164, 364, or SG1 battery equivalent, go for a battery labeled as SR621SW (SR621 Silver-Watch) battery - it is a silver-oxide battery with stable voltage and high capacity.