SR621SW/364 Watch Battery Equivalents and Replacements
SR621SW/364 batteries are non-rechargeable 1.55V silver-oxide button/coin-cell batteries, commonly used in watches, calculators, toys, credit-card size devices, medical instruments, and similar.
SR621SW/364 batteries are manufactured by many popular battery brands, but often feature additional labels which, in combination with very similar alkaline batteries, may lead to certain confusion among the users.
Published: March 11, 2023.
SR621SW/364 Battery Features and Specifications
SR621SW/364 battery features physical dimensions of (D x W) 6.8 x 2.1 mm (~0.2677 x 0.0826 inches), a nominal voltage of 1.55V, a cutoff voltage of 1.2V, and an average nominal capacity of ~20 mAh.
Note: Nominal capacity depends on the battery age, temperature, discharge current, and similar.
SR621SW/364 battery is based on the silver-oxide battery chemistry and is often labeled as SR621, SR621W, SR60, 164, 364, SG1, etc. But, their labels almost always include "SR621SW" and "364".
SR621SW/364 batteries on average feature shelf life between 2-5 years, sometimes even more.
Alkaline 6.8 x 2.1 mm non-rechargeable batteries are somewhat cheaper than silver-oxide 6.8 x 2.1 mm batteries and are labeled as LR621 battery, LR60 battery, AG1 battery, and similar.
Alkaline 6.8 x 2.1 mm batteries feature a nominal voltage of 1.5V, a cutoff voltage of 0.8-0.9V, smaller capacity which also depends on the discharge characteristics, shorter shelf-life, and less table output voltage.
Thus, alkaline 6.8 x 2.1 mm batteries are sometimes used in toys and similar applications where stable voltage is not of vital importance.
Because of these reasons, silver-oxide 6.8 x 2.1 mm batteries are used much more often than alkaline 6.8 x 2.1 mm batteries.
SR621SW/364 Batteries Comparison Table
The following comparison table lists some of the most common SR621SW/364 batteries with their most important features and specifications:
| Battery |
Chemistry Nominal and Cutoff Voltages |
Capacity Discharge Current |
Operating Temperature Annual Self-Discharge Rate |
| Duracell D364 |
Silver Oxide 1.55V, 1.2V |
20 mAh 68k1Ω down to 1.2V @20°C 33.2μA @1.52V 68k1Ω @20°C |
0°C to +60°C <10% @20°C |
| Energizer 364/363 |
Silver Oxide 1.55V, 1.2V |
19 mAh 68kΩ down to 1.2V @21°C 21μA @1.46V 68kΩ @21°C |
- ~2% @20°C |
| Maxell SR621SW |
Silver Oxide 1.55V, 1.2V |
18 mAh 47kΩ down to 1.2V @20°C 30μA @1.55V 47kΩ @20°C |
-10°C to +60°C - |
| muRata SR621 |
Silver Oxide 1.55V, 1.2V |
20 mAh 47kΩ down to 1.2V @23°C 30μA @1.55V 47kΩ @23°C |
-10°C to +60°C - |
| Renata 364 SR621SW | Silver Oxide 1.55V, 1.2V |
19 mAh 47kΩ down to 1.2V @20°C 33.2μA starting drain over 47kΩ @20°C |
-10°C to +60°C <5% @20°C |
| Seiko SR621SW |
Silver Oxide 1.55V, 1.2V |
23 mAh 30kΩ down to 1.2V @23°C 40μA |
-10°C to +60°C - |
| Varta V 364 MF |
Silver Oxide 1.55V, 1.2V |
17 mAh 68kΩ down to 1.2V @20°C ~22μA @1.55V 68kΩ @20°C |
0°C to +60°C <10% @20°C |
Obviously, there are also other very popular battery models on the market.
SR621SW/364 Batteries Frequently Asked Questions (FAQ)
Here are some of the most common Frequently Asked Questions (FAQ) about SR621SW/364 batteries and watch batteries in general:
What size battery is SR621SW? What size is a 364 battery?
SR621SW/364 batteries are button/coin cell batteries featuring physical dimensions of (D x W) 6.8 x 2.1 mm (~0.2677 x 0.0826 inches).
What is the equivalent battery for the SR621SW battery? What battery is equivalent to 364 batteries?
SR621SW/364 batteries are silver-oxide batteries that are often labeled including SR621, SR621W, SR60, 164, 364, SG1, etc. - all these batteries are directly compatible with SR621SW/364 batteries since these are the same batteries, just different labels.
However, alkaline LR621, LR60, AG1 button/coin cell batteries are somewhat compatible with SR621SW/364 batteries - alkaline batteries feature somewhat smaller initial voltage, less stable output voltage, smaller capacity, and shorter shelf-life.
If silver-oxide SR621SW/364 batteries are unavailable, alkaline LR621, LR69, or AG1 button/coin cells may be used, but with potential issues during operation.
Is 377 battery the same as SR621SW? Are 377 and 364 batteries interchangeable?
377 battery is a silver-oxide 6.8 x 2.6 mm battery - it is 0.5 mm (0.019685 inches) higher than the SR621SW/364 battery.
Although 0.5 mm doesn't appear much, it is enough to cause warps and deformations if the 377 battery is forced/pushed in the battery compartment intended for SR621SW/364 battery.
On the other hand, if the SR621SW/364 battery is placed in the battery compartment intended for 377 battery, it may function, but it may also have issues with contacts - not recommended.
What battery is comparable to the SR621SW battery?
Any 1.55V silver-oxide 6.8 x 2.1 mm battery from reputable brands is comparable/compatible with the SR621SW battery regardless of its label(s).
Can you interchange watch batteries?
If the batteries are of the same size and chemistry, yes. If they are not of the same size and chemistry, they should not be considered interchangeable/compatible.
SR621SW/364 Safety Issues
SR621SW/364 batteries are very small batteries with relatively small output voltage and capacity.
However, they are shiny little objects that can be very attractive to pets and kids - hence, SR621SW/364 and similar batteries are packaged in "pets and kids safe packages".
Although SR621SW/364 batteries don't contain mercury, cadmium, and other toxic elements, if the SR621SW/364 batteries get swallowed they can cause chemical burns due to the electrolysis and mechanical injuries of various degrees.
If SR621SW/364 batteries or any similar batteries get swallowed, contact the nearest emergency center/veterinarian, explain to them what happened and act according to their instructions.
Few Final Words
SR621SW/364 batteries feature stable output voltage, relatively long shelf life, and considering their size good capacity.
Although they tend to be somewhat more expensive when compared with similar alkaline batteries, always go for silver-oxide batteries, especially if You need these batteries for watches, medical instruments, credit-card devices, and similar.
