The two main battery naming systems
Most batteries you encounter fall into one of two naming systems. Cylindrical batteries like AA and AAA follow an older American National Standards Institute (ANSI) system. Coin and button cells like the CR2032 and LR44 follow the IEC (International Electrotechnical Commission) standard, which is more widely used internationally.
Both systems encode useful information — chemistry, shape, and size — directly into the battery's name. Here's how to read each one.
Coin and button cell batteries — the IEC system
This is where the codes look most confusing, but the logic is actually quite elegant. Take a CR2032 and break it apart:
So CR2032 literally means: a round lithium battery, 20mm wide and 3.2mm thick. If you ever find a battery marked CR2025, you now know it's the same 20mm diameter but only 2.5mm thick — slightly flatter than a CR2032.
Now let's decode LR44
Note that for some battery series, the number after R is a standardised size code rather than a direct millimetre measurement. The CR2032 convention (where the numbers directly equal the dimensions) is used for larger lithium coin cells, but older button cell codes like LR44 predate that system.
What the chemistry letter tells you
The first letter in a coin or button cell code is the most practically important — it tells you the chemistry, which determines the voltage. Getting this wrong means your device may not work correctly even if the battery physically fits.
| Letter | Chemistry | Voltage | Common uses |
|---|---|---|---|
| C | Lithium manganese dioxide | 3V | CR2032, CR2025, CR2016 — car key fobs, watches, calculators |
| L | Alkaline | 1.5V | LR44, LR41 — thermometers, toys, small lights |
| S | Silver oxide | 1.55V | SR44, SR626 — watches requiring precise voltage |
| Z | Zinc-air | 1.4V | Hearing aids — activated by removing a tab to expose air |
| B | Lithium carbon monofluoride | 3V | BR2032 — same size as CR2032, wider temperature range |
Cylindrical batteries — AA, AAA and the rest
The AA and AAA naming system comes from the American ANSI standard and is less logical — the letters don't directly encode chemistry or dimensions. Instead, they're simply size designations that became globally adopted.
| Name | Diameter | Length | Voltage | Common uses |
|---|---|---|---|---|
| D | 34.2mm | 61.5mm | 1.5V | Large torches, radios, some toys |
| C | 26.2mm | 50mm | 1.5V | Medium torches, portable radios |
| AA | 14.5mm | 50.5mm | 1.5V | Remotes, clocks, toys, keyboards |
| AAA | 10.5mm | 44.5mm | 1.5V | TV remotes, bathroom scales, small devices |
| 9V | 48.5 × 26.5 × 17.5mm (rectangular) | 9V | Smoke alarms, guitar pedals, multimeters | |
Despite what the naming might suggest, more As does not always mean smaller in all contexts — AAAA batteries exist and are smaller than AAA, but they're relatively rare. For everyday use, AA is larger than AAA, and that's the relationship that matters.
Why does the same battery have so many different names?
This is probably the most confusing thing about buying batteries. The CR2032 is also sold as DL2032, ECR2032, and BR2032. The LR44 is also known as AG13, 357, A76, SR44W, and G13. They are all electrically equivalent — only the label differs.
There are a few reasons for this. First, different countries and standards bodies developed their own naming conventions before global standardisation. Second, battery manufacturers like Duracell (DL prefix), Energizer, and Varta created their own internal part numbers for marketing purposes. Third, the IEC standard was updated over time, leaving older codes still in circulation.
A note on accuracy
The IEC naming conventions described in this guide reflect the standard system used by most manufacturers. However, battery naming is not perfectly consistent across all brands and regions — some manufacturers use proprietary codes or apply naming conventions slightly differently to older battery series. If you are replacing a battery in a medical device, hearing aid, or any safety-critical equipment, always consult your device manual or the manufacturer directly rather than relying on naming conventions alone.