LR621 battery: equivalents & specs
The LR621 is a tiny 1.5 volt alkaline button cell, 6.8 mm across and 2.1 mm tall, sold under the codes AG1, LR60 and 164. Its silver-oxide twin is the SR621SW, better known as the 364, one of the most common small watch batteries in the world.
Same battery, other names
Every code below is the exact same cell as LR621. Any of them will fit and work identically.
Compatible replacements
- SR621SW / 364: Silver-oxide equivalent, the standard small watch cell, with flatter voltage and longer life.
Buying and replacement notes
You will mostly meet the AG1 as the factory cell inside inexpensive watches. Battery counters rarely stock the alkaline version at all; they carry the 364 because nearly everyone replacing this size is servicing a watch. Fit the 364 and you get two to three years of accurate running instead of about a year with declining accuracy from the alkaline.
Commonly used in
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⚠️ Keep away from children. Swallowed button batteries, especially 20 mm lithium coins, cause severe injury within hours. If a child swallows one, call the 24/7 National Battery Ingestion Hotline (US) at 800-498-8666 or poison control at 800-222-1222 immediately. What every parent should know.