How do I find out which battery my watch takes?

Open the caseback and read the code on the old battery: it's printed on the flat side, such as 377 or SR626SW. If the battery is gone, the watch's manual or the movement's caliber number will tell you, and a watch shop can measure the compartment.

Are watch batteries universal?

No. Watches use dozens of sizes that differ by fractions of a millimeter. A battery with the right diameter but the wrong thickness won't make contact or won't let the caseback close, so match the code exactly or use one of its listed equivalents.

Can I use an alkaline battery instead of silver oxide?

It fits, since alkaline and silver-oxide cells of the same size share dimensions. But alkaline cells start at 1.5 volts and keep dropping as they drain, while silver oxide holds about 1.55 volts until nearly empty. A quartz watch runs longer and keeps better time on silver oxide.

What does SW mean on a watch battery?

SW marks a low-drain silver-oxide cell, made for ordinary analog watches. W marks a high-drain cell for watches with a backlight, alarm or chronograph. A high-drain cell works in any watch; a low-drain one can struggle in a watch with those features.

Watch battery size chart

The same watch battery is sold under five or six names. A 377 is also an SR626SW, an AG4 and an LR626, depending on the brand and the chemistry. This chart lists 37 common sizes with every name for each, so you can match the code on your old battery to one you can buy.

Type the code printed on your old battery

Most searched sizes

Silver-oxide watch batteries (1.55 V)

Almost every analog quartz watch uses one of these, sorted from smallest to largest.

Battery	Size	Also sold as
337	4.8 × 1.65 mm	SR416SW
335	5.8 × 1.25 mm	SR512SW
317	5.8 × 1.65 mm	SR516SW
379	5.8 × 2.1 mm	SR521SW, LR521, AG0, LR63, SR63
319	5.8 × 2.7 mm	SR527SW
321	6.8 × 1.65 mm	SR616SW
364	6.8 × 2.1 mm	SR621SW, SR621W, 363, LR621, AG1, 164, LR60, SR60
377	6.8 × 2.6 mm	SR626SW, SR626W, 376, LR626, AG4, 177, LR66, SR66
346	7.9 × 1.25 mm	SR712SW
341	7.9 × 1.45 mm	SR714SW
315	7.9 × 1.65 mm	SR716SW
362	7.9 × 2.1 mm	SR721SW, SR721W, 361, LR721, AG11, 162, LR58, SR58
397	7.9 × 2.6 mm	SR726SW, SR726W, 396, LR726, AG2, 196, LR59, SR59
329	7.9 × 3.1 mm	SR731SW
LR41	7.9 × 3.6 mm	SR41SW, SR41W, 384, 392, AG3, 192, L736, 392A, SR736, SR41
393	7.9 × 5.4 mm	SR754SW, SR754W, 309, LR754, AG5, 193, LR48, SR48
373	9.5 × 1.6 mm	SR916SW
371	9.5 × 2.05 mm	SR920SW, SR920W, 370, LR920, LR921, AG6, 171, LR69, SR69
395	9.5 × 2.7 mm	SR927SW, SR927W, 399, LR927, AG7, 195, LR57, SR57
394	9.5 × 3.6 mm	SR936SW, SR936W, 380, LR936, AG9, 194, LR45, SR45
366	11.6 × 1.65 mm	SR1116SW
381	11.6 × 2.05 mm	SR1120SW, SR1120W, 391, LR1120, AG8, 191, LR55, SR55
LR1130	11.6 × 3.05 mm	SR1130SW, SR1130W, 390, 389, AG10, 189, LR54, L1131, SR54
344	11.6 × 3.6 mm	SR1136SW
386	11.6 × 4.2 mm	SR43SW, SR43W, 301, LR43, AG12, 186, L1142, SR1142, SR43
LR44	11.6 × 5.4 mm	SR44SW, SR44W, 303, 357, AG13, A76, L1154, L1154F, 1166A, 357A, SR1154, SR44

Lithium coin cells (3 V)

Used in digital watches and many other gadgets. Never put one in a watch made for a 1.55 V silver-oxide cell.

Battery	Size	Also sold as
CR1216	12.5 × 1.6 mm	DL1216, ECR1216, BR1216
CR1220	12.5 × 2 mm	DL1220, ECR1220, BR1220
CR1225	12.5 × 2.5 mm	DL1225, ECR1225, BR1225
CR1616	16 × 1.6 mm	DL1616, ECR1616, BR1616
CR1620	16 × 2 mm	DL1620, ECR1620, BR1620
CR1632	16 × 3.2 mm	DL1632, ECR1632, BR1632
CR2016	20 × 1.6 mm	DL2016, ECR2016, BR2016
CR2025	20 × 2.5 mm	DL2025, ECR2025, BR2025
CR2032	20 × 3.2 mm	DL2032, ECR2032, BR2032
CR2430	24.5 × 3 mm	DL2430, ECR2430, BR2430
CR2450	24.5 × 5 mm	DL2450, ECR2450, BR2450

How to read a battery code

Silver-oxide codes follow one international standard. In SR626SW, S is silver oxide and R is round. 6 is the diameter class (6.8 mm), and 26 is the height in tenths of a millimeter (2.6 mm). The ending SW marks a low-drain cell and W a high-drain one.

The diameter classes are 4 (4.8 mm), 5 (5.8 mm), 6 (6.8 mm), 7 (7.9 mm), 9 (9.5 mm) and 11 (11.6 mm). Swap the S for an L and you have the alkaline cell of the same size: LR626. The AG numbers (AG0 to AG13) are another set of names for the alkaline sizes.

Lithium coin cells read the same way: a CR2032 is 20 mm across and 3.2 mm thick. DL (Duracell) and ECR (Energizer) are the same cell under brand prefixes. BR cells use a different lithium chemistry that fits the same holder but delivers less current.

The three-digit numbers, such as 377, 371 and 395, come from Energizer and Renata, and most brands now print them too. Low-drain and high-drain versions of the same size get different numbers, like 377 and 376.

Getting the battery changed

A battery is the cheapest repair a watch gets. Across the 41 shops in our watch repair directory that list a price, a battery change costs $4.99 to $115, with a median of $15. A shop will also replace a dried-out gasket and pressure-test a water-resistant watch, which you can't do at home. See watch battery replacement near you, what a battery replacement costs, or how to change a watch battery yourself.

Questions

How do I find out which battery my watch takes?: Open the caseback and read the code on the old battery: it's printed on the flat side, such as 377 or SR626SW. If the battery is gone, the watch's manual or the movement's caliber number will tell you, and a watch shop can measure the compartment.
Are watch batteries universal?: No. Watches use dozens of sizes that differ by fractions of a millimeter. A battery with the right diameter but the wrong thickness won't make contact or won't let the caseback close, so match the code exactly or use one of its listed equivalents.
Can I use an alkaline battery instead of silver oxide?: It fits, since alkaline and silver-oxide cells of the same size share dimensions. But alkaline cells start at 1.5 volts and keep dropping as they drain, while silver oxide holds about 1.55 volts until nearly empty. A quartz watch runs longer and keeps better time on silver oxide.
What does SW mean on a watch battery?: SW marks a low-drain silver-oxide cell, made for ordinary analog watches. W marks a high-drain cell for watches with a backlight, alarm or chronograph. A high-drain cell works in any watch; a low-drain one can struggle in a watch with those features.