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Home › Batteries › 381
Watch battery

381 is the same as SR1120SW

1What it is2Safety3Other names4Facts5Buy it
  1. 1

    What it is

    SR1120SW+ 1.55V

    381 is just another name for SR1120SW. Same battery, different label, so you can buy either one.

    Search Amazon for 381As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

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  2. 2

    Safety first

    Keep away from children and pets

    A swallowed coin or button battery can cause serious burns inside the body within 2 hours. If you think one was swallowed, get emergency help right away.

    Swallowed one? What to do now →
  3. 3

    Names you might see in the store

    All of these are the same battery. Any of them will work.

    SR1120SW
  4. 4

    Quick facts

    Size
    About as wide as a shirt button
    Thickness
    As thick as 3 credit cards stacked
    Power
    1.55 volts
    Keeps in a drawer for
    About 5 years
    Rechargeable?
    No, use once
    Found in things like
    Analog watches
  5. 5

    Where to buy it

    As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

    Amazon searchEnergizer listings, any pack sizeSearch Amazon for Energizer 381
    See results on Amazon →
    Amazon searchMulti-packs from any brandSearch Amazon for 381 (SR1120SW) multi-packs
    See results on Amazon →
    Amazon searchDuracell listings, the same batterySearch Amazon for Duracell SR1120SW
    See results on Amazon →

    Buttons open amazon.com 🇺🇸, picked from your country.

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See it at real size

SR1120SW next to a US quarter and an AA battery. “Real size” matches your hand once your screen is set up in Measure it.

SR1120SWThickness 2.1US quarterAA

What do the letters mean?

Battery names are a code. Here’s how to read 381:

3Watch-industry 300 series (Renata/Energizer numbering)
81Size and drain code. Maps to SR1120SW, 11.6 × 2.1 mm

The same battery from each brand

BrandTheir name for it
Official nameSR1120SW
Energizer381
Murata (formerly Sony)SR1120SW
Renata (Swiss)381
MaxellSR1120SW

Exact measurements

Width
11.6 mm (0.457 in)
Thickness
2.1 mm
Voltage
1.55V (empty at 1.2V)
Energy stored
50 mAh
Weight
—
Made with
Silver oxide
Works between
-10 … 60 °C
Official code
SR1120SW

Questions people ask

Is 381 the same as SR1120SW?

Yes. They’re the same battery with different names. You might also see SR1120SW.

How long will a spare keep in a drawer?

About 5 years if it stays cool and dry.

Can I recharge it?

No. Never try to recharge it.

Which way up does it go?

Usually with the side marked “+” facing you or facing up. Look at how the old one sits before you take it out.

SR1120SW+ 1.55V
SR1120SWWatch battery
Search Amazon for 381As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

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1What it is2Safety3Other names4Facts5Buy it