379 Battery Equivalent
379
Fourth most common watch battery
379 and SR521SW are exactly the same battery. The fourth most widely used watch battery in the world. Its compact 5.8mm diameter makes it one of the smallest silver oxide watch batteries in common use.
Voltage
1.55V
Chemistry
Silver Oxide
Dimensions
5.8mm × 2.1mm
Typical battery life
2–3 years
All 379 equivalents
| Battery code | Type | Compatible? |
|---|---|---|
| 379 | Silver oxide | ✓ Direct replacement |
| SR521SW | Silver oxide | ✓ Direct replacement (IEC code) |
| SR63 | Silver oxide | ✓ Direct replacement |
| D379 | Silver oxide | ✓ Direct replacement (Duracell) |
| V379 | Silver oxide | ✓ Direct replacement (Varta) |
| SB-AC / SB-DC | Silver oxide | ✓ Direct replacement (Seiko) |
| 280-59 | Silver oxide | ✓ Direct replacement (Citizen) |
| 50 | Silver oxide | ✓ Direct replacement (Renata) |
| SG0 / AG0 | Silver oxide | ✓ Direct replacement |
| LR521 | 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 379
Found in many small-case and slim quartz watches from Seiko, Citizen, Casio, and various fashion brands. Its small 5.8mm diameter is distinctive — if your current battery is noticeably tiny, this is likely the correct size.
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 379 batteries on Amazon
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