381 / SR1120SW battery equivalent

Also sold as SR1120SW. 1.55 V with a flat discharge curve — the usual choice for quartz watches.

Chemistry

Silver oxide

Voltage

1.55 V

Size

11.6 × 2.1 mm

Inches

0.457 × 0.083 in

Drain

Low drain (SW)

Typical capacity

~50 mAh

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Equivalents by brand

Brand	Number
Renata	381
Energizer / Eveready	381
Maxell / Panasonic / Sony	SR1120SW
Varta	V381
Rayovac	381
Duracell	D381
Bulova	317
Citizen	280-27
Seiko	SB-AS/DS
IEC	SR55
IEC size	SR1121

Also known as

SR1120SWV381D381317280-27SB-AS/DSSB-ASSB-DSSR55SR1121SR1120SG8

What it fits

Analog watches. Confirm the printed number or measure the old cell before you buy — a 0.5 mm height difference will not seat correctly.

IEC names encode chemistry and size. SR is silver oxide, LR is alkaline, and CR is 3 V lithium. The digits are diameter and height in tenths of a millimeter, so SR1120SW is about 11.6 mm across and 2.1 mm thick.

Same size, different drain

These cells share the 11.6 × 2.1 mm can. Low-drain (SW) is for simple analog watches. High-drain (W) handles lights, alarms, and chronographs. A modern multi-drain cell can usually cover both.

FAQ

What battery replaces a 381?

Any of these are common equivalents: 381, SR1120SW, V381, D381, 317, 280-27, SB-AS/DS, SB-AS. They are 1.55 V silver oxide cells, 11.6 × 2.1 mm.

Is 381 the same as SR1120SW?

Yes — SR1120SW is the IEC / Japanese-brand name for the same 381 cell.

What devices use a 381?

Analog watches