What do the letters on a battery mean?

In an IEC code the first letter is the chemistry and R means a round cell: L is alkaline, S is silver oxide, C is lithium manganese dioxide, B is lithium carbon monofluoride and P is zinc air. Anything else in front, such as AG, DL or ECR, is a trade or brand number rather than an IEC code.

What do the numbers on a button battery mean?

A four-digit group is the case size: the first two digits are the diameter in whole millimetres, rounded down, and the last two are the height in tenths of a millimetre. A shorter number, such as the 44 in LR44, is a reference number and says nothing about the size.

What does SW mean on a watch battery?

It is the drain the cell is built for, not part of the size. Manufacturers mark low-drain cells SW, for something like a plain quartz movement, and high-drain cells W, for a watch with a backlight or an alarm. Both are the same size and voltage.

Is LIR2032 the same as CR2032?

No. LIR is rechargeable lithium-ion in the same case: 3.6 V to 4.2 V when charged, a fraction of the capacity, and only for a device built to charge it.

The code on my battery is not here. What now?

This decoder holds 310 codes across 84 cells. If yours is not one of them, measure the cell instead: the diameter and height identify it regardless of what is printed on it.

Battery Code Decoder

Type the code stamped on the cell, however it is punctuated, and find out which battery it is. 310 codes across 84 cells, plus what the letters and digits themselves mean for a code that is not here.

The code printed on the cell

Spaces and dashes do not matter. Try , , , , .

Type the code exactly as it is printed. If the printing has worn off, measure the cell instead and use the size finder.

The chemistry letters

An IEC code puts the chemistry first and the shape second, so the first two characters tell you what the cell is made of and that it is round.

Letter	Chemistry	Nominal voltage	Example
LR	Alkaline manganese dioxide	1.5 V	LR44
SR	Silver oxide	1.55 V	SR44
CR	Lithium manganese dioxide	3 V	CR2032
BR	Lithium carbon monofluoride	3 V	BR2335
PR	Zinc air	1.4 V	PR44

Source: IEC 60086-1, via Wikipedia's battery nomenclature summary. These are the nominal voltages the standard gives each system; a cell's own page shows the voltage recorded for it, which can differ by a few hundredths.

The R is the shape: round. It is the reason nearly every code here has one, and why its absence usually means you are looking at a trade number rather than an IEC code.

The digits

Four digits are a measurement. The first two are the diameter in whole millimetres and the last two are the height in tenths of a millimetre, so CR2032 is 20 mm across and 3.2 mm thick. The diameter is rounded down, which is why a CR1220 measures 12.5 mm rather than 12.0 mm. Where a code matches a cell in this chart, the decoder shows the measured size from the cell's record instead of the figure the digits imply. The convention is the truncated diameter in millimetres followed by the height in tenths of a millimetre, as IEC 60086-1 sets out.

A shorter number is not a measurement at all. The 44 in LR44 is a reference number: the cell is 11.6 mm across and 5.4 mm thick. The same cell written the long way is LR1154, which does describe it.

The suffix, and prefixes that are not IEC codes

On silver-oxide watch cells, manufacturers mark low-drain cells SW and high-drain cells W: Renata, Maxell and Energizer all number them this way. The letters are not part of the size, and a cell carrying one will be the same dimensions as the same number without it.

The prefixes the decoder recognises that are not IEC codes:

AG — Generic trade number, common on generic and own-brand alkaline cells
SG — Generic trade number for the silver-oxide cell of the same size
DL — Duracell's part number for a lithium coin cell
ECR — Energizer's part number for a lithium coin cell
KCR — Kodak's part number for a lithium coin cell
V — Varta part numbers often start with V
ZA — Zinc air, a hearing-aid cell

One prefix matters more than the rest: LIR looks like an IEC lithium code and is not one. It is a rechargeable lithium-ion cell in a coin-cell case, and it is never a substitute for the CR of the same number.

Reading a battery code

What do the letters on a battery mean?: In an IEC code the first letter is the chemistry and R means a round cell: L is alkaline, S is silver oxide, C is lithium manganese dioxide, B is lithium carbon monofluoride and P is zinc air. Anything else in front, such as AG, DL or ECR, is a trade or brand number rather than an IEC code.
What do the numbers on a button battery mean?: A four-digit group is the case size: the first two digits are the diameter in whole millimetres, rounded down, and the last two are the height in tenths of a millimetre. A shorter number, such as the 44 in LR44, is a reference number and says nothing about the size.
What does SW mean on a watch battery?: It is the drain the cell is built for, not part of the size. Manufacturers mark low-drain cells SW, for something like a plain quartz movement, and high-drain cells W, for a watch with a backlight or an alarm. Both are the same size and voltage.
Is LIR2032 the same as CR2032?: No. LIR is rechargeable lithium-ion in the same case: 3.6 V to 4.2 V when charged, a fraction of the capacity, and only for a device built to charge it.
The code on my battery is not here. What now?: This decoder holds 310 codes across 84 cells. If yours is not one of them, measure the cell instead: the diameter and height identify it regardless of what is printed on it.

If the code has worn off

Measure the cell instead. Two numbers identify it exactly, and the size finder will list every cell that matches, with the verdict for each.