Watch Battery Guide

Jump to: Battery chart | Finding the right battery | Common questions

Watch Battery Size Chart and Cross Reference

How to Find the Right Battery for Your Watch

Start with the battery that is already fitted. When you open the caseback you will see the number printed on its flat side, normally a three digit figure such as 371 or a maker's code such as SR920SW, and quite often both together. The lettering is tiny, so a quick wipe and a bright light make it far easier to read. If you prefer not to open the watch yet, check the instruction booklet or the box it came in, as these usually name the battery, and Casio, Seiko and Citizen all publish battery details for their movements. Type whatever number you find into the search box in the chart above and every matching battery we stock will appear.

Pay attention to the last letters of the code as well. SW tells you the cell is made for low drain analogue watches, while a code ending in W alone is built for high drain use in digital watches and models with lights, alarms or chronographs. For a watch with any of those features, the W version is the better choice wherever it is available.

Common Questions About Watch Batteries

Which watch battery sizes are most common?

The sizes we see most often in everyday analogue watches include 377 (SR626SW), 364 (SR621SW), 371 (SR920SW), 379 (SR521SW), 395 (SR927SW) and 321 (SR616SW). Bigger and older watches frequently use 357 (SR44W), 303 (SR44SW), 392 (SR41W) or 384 (SR41SW). Plenty of digital watches, Casio included, run on 3 volt lithium coin cells such as CR2016 or CR2025 rather than silver oxide.

Are silver oxide and lithium batteries interchangeable?

No. Silver oxide cells run at 1.55 volts and keep a very even output until they are almost spent, which is why nearly all analogue quartz watches use them. Lithium coin cells run at 3 volts, are generally larger and are mainly found in digital watches. Fitting the wrong type can stop a watch or damage it, so always match the number on the old battery.

Why choose Japanese watch batteries?

Every silver oxide battery on this page is made in Japan by Maxell, Murata, Seiko or Seizaiken. They are genuine, mercury free cells made to the same international sizes as every other brand, so whichever you pick, the right number will fit your watch. Matching the number is what really counts, and any of these brands will do the job well.

How long will a new watch battery last?

A silver oxide battery in an ordinary analogue watch typically lasts around two to five years, although this depends on the movement and the size of the cell. Chronographs, alarms and lights all draw extra power, so watches with these features usually need a new battery sooner.

Is it safe to change a watch battery at home?

For many watches it is, as long as you have a suitable caseback opener and plastic tweezers. Take note of which way up the old battery is fitted, put the new one in exactly the same way, and handle it by the edges so the flat faces stay clean. A water resistant watch will need its seal checked afterwards to stay water tight, so for divers' watches and anything valuable it is wise to use a watch repairer.

My battery is not listed. What should I do?

Contact us with the number printed on your old battery and we will track down the correct replacement for you.