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Silver-oxide watch (SR)

SR721SW battery: equivalents & specs

The SR721SW, retail number 362, is a mainstream 1.55 volt silver-oxide watch battery: 7.9 mm across, 2.1 mm tall, roughly 25 mAh. It is a staple size for midsize analog quartz movements, with the 361 (SR721W) as its high-drain sibling.

SR721SW battery drawing: 7.9 mm across, 2.1 mm thick SR721SW 1.55V + ⌀ 7.9 mm 2.1 mm
SR721SW, face and side profile, drawn to scale: 7.9 mm across, 2.1 mm thick.
Voltage
1.55 V
Size (D×H)
7.9 × 2.1 mm
Chemistry
Silver oxide (Ag2O)
Capacity
24-27 mAh

Same battery, other names

Every code below is the exact same cell as SR721SW. Any of them will fit and work identically.

362SR58V362SR721W (361, high drain)

Compatible replacements

  • LR721 / AG11: Alkaline same-size cell; usable in toys, not recommended for watches.

Buying and replacement notes

The 362 is one of the sizes every watch counter keeps in depth, alongside the 364, 377 and 371. Choose the 362 for plain analog watches and the 361 for movements that drive lights, alarms or chronograph hands. The alkaline AG11 shares the case dimensions but not the performance; it belongs in novelty gadgets, not watches.

Commonly used in

analog quartz watchesmidsize watch movements

Need a replacement?

Shop SR721SW batteries on Amazon →

Comparisons

LR721 vs SR721

⚠️ 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.

Frequently asked questions

What replaces a 362 battery?
Any SR721SW is the same cell: 1.55 V silver oxide, 7.9 x 2.1 mm, about 25 mAh. The 361 (SR721W) is the high-drain version in the identical case and also fits. The alkaline AG11/LR721 fits physically but gives markedly shorter watch life.
What is the difference between 361 and 362?
Chemistry tuning, not size. The 362 (SW) uses a sodium-hydroxide electrolyte suited to constant microamp drains in simple watches. The 361 (W) uses potassium hydroxide for high pulse currents in watches with extra functions. Both measure 7.9 x 2.1 mm.
How long does a 362 last in a watch?
Two to three years is typical for an analog quartz movement in good order. If the second hand starts jumping several seconds at a time, many movements are signaling end of battery life; replace the cell soon to avoid it dying and leaking in place.

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