321 Battery Equivalent
321
Very thin watch battery — 1.65mm
321 and SR616SW are exactly the same battery. At only 1.65mm thick it is one of the thinnest silver oxide watch batteries in common use. It shares the same 6.8mm diameter as the 377 and 364 but is much thinner than both.
Voltage
1.55V
Chemistry
Silver Oxide
Dimensions
6.8mm × 1.65mm
Typical battery life
1–3 years
⚠ Check thickness carefully. The 321 shares its 6.8mm diameter with the 377 (2.6mm) and 364 (2.1mm) but at just 1.65mm it is significantly thinner. Fitting a thicker battery can damage the caseback or movement. Always confirm the exact code on your existing battery.
All 321 equivalents
| Battery code | Type | Compatible? |
|---|---|---|
| 321 | Silver oxide | ✓ Direct replacement |
| SR616SW | Silver oxide | ✓ Direct replacement (IEC code) |
| SR65 | Silver oxide | ✓ Direct replacement |
| D321 | Silver oxide | ✓ Direct replacement (Duracell) |
| V321 | Silver oxide | ✓ Direct replacement (Varta) |
| SB-AF / SB-DF | Silver oxide | ✓ Direct replacement (Seiko) |
| 280-73 | Silver oxide | ✓ Direct replacement (Citizen) |
| 38 | Silver oxide | ✓ Direct replacement (Renata) |
| DA | Silver oxide | ✓ Direct replacement (Maxell) |
| LR616 | Alkaline | ⚠ Same size — use silver oxide for watches |
Silver oxide vs alkaline — does it matter?
Always use silver oxide in watches — not alkaline. Alkaline equivalents have a declining voltage curve — your watch will run slower as the battery drains. Silver oxide maintains a steady 1.55V until nearly depleted, giving accurate timekeeping throughout its life.
Watches that use 321
Found in slim and ultra-thin quartz watch movements from Seiko, Citizen, and various Swiss and fashion brands. Its 1.65mm profile is ideal for very thin case designs.
Always check the code on your existing battery or the caseback of your watch. If unsure, a jeweller can confirm the correct size without replacing the battery.
Buy 321 batteries on Amazon
Affiliate link · Silver oxide recommended
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