Battery naming systems explained: IEC, ANSI and AG codes

Button batteries carry several names because three naming systems coexist. The international IEC standard produces codes like LR44 and CR2032, the American ANSI system assigns numbers like 357 and 377, and battery factories in Asia use their own AG and SG shorthand. All three can point to exactly the same physical cell.

What do the letters in an IEC battery code mean?

The IEC 60086 standard builds a battery name from two letters and a string of digits. The first letter declares the chemistry, which also tells you the voltage. The second letter, almost always R, describes the shape: round. The digits that follow describe the size of the can.

Chemistry is the part people trip over most, so here is the full decoder.

Suffixes carry meaning too. On silver oxide watch cells, a final W means the cell meets the IEC high drain requirements, while SW marks a low drain cell for simple analog movements. That single letter matters more than it looks, and the watch battery guide covers it in detail.

Two more prefixes show up in electronics repair. LIR marks a rechargeable lithium ion cell in a coin format, so an LIR2032 fits a CR2032 holder but delivers 3.6 volts, enough to damage circuits designed for 3 volts. ML and VL mark rechargeable lithium chemistries at 3 volts used for memory backup on motherboards and in some car key fobs. Never drop a plain CR cell into a device that charges its battery, and never charge a CR cell. The prefix is the only warning you get.

How do you decode CR2032?

Take CR2032 apart piece by piece. C means lithium manganese dioxide chemistry at 3 volts. R means round. The first two digits, 20, give the diameter in millimeters. The last two digits, 32, give the height in tenths of a millimeter, so 3.2 mm. Put together: a round lithium coin, 20 mm across and 3.2 mm tall. Its sibling CR2025 shares the 20 mm diameter but stands only 2.5 mm tall, and CR2016 trims the height to 1.6 mm. The scheme means you can often read a replacement size straight off the code, provided the chemistry letter also matches.

Small silver oxide cells follow the same idea with one wrinkle. In SR626SW, the trailing 26 is the height, 2.6 mm, while the leading 6 identifies the 6.8 mm case size from the standard's diameter table rather than stating it directly.

One caveat: the oldest codes predate this dimensional logic. The 44 in LR44 is a legacy catalog number, not a measurement. The same can measured the modern way is LR1154, which is why both names appear on packaging for a cell that is 11.6 mm wide and 5.4 mm tall.

What are ANSI and NEDA numbers?

Before the IEC system spread, the American National Standards Institute and the National Electronic Distributors Association assigned plain catalog numbers. These survive today mostly on watch and hearing aid batteries sold in North America. The numbers encode nothing. 357 is simply the entry for the high drain silver oxide cell that IEC calls SR44W. 377 maps to SR626SW. 1166A is the alkaline LR44. 1166A and LR44 name one cell; 357 and SR44W name another; the two cells share a case but not a chemistry, which is exactly why LR44 vs 357 deserves its own comparison.

Photo lithium cells kept ANSI numbers as well. The CR123A camera battery is also sold as 5018LC, and CR2032 appears in old catalogs as 5004LC. If a manual only lists a bare number, it is almost certainly one of these ANSI entries.

What are AG and SG codes?

Walk through any discount store and you will find blister packs labeled AG1, AG3, AG13. These are manufacturer codes that originated with Asian battery plants. AG stands for alkaline and a G size series; SG marks the silver oxide twin in the same can. AG13 is LR44. SG13 is SR44. AG3 is LR41, AG4 is LR626, and AG10 is LR1130. The codes are convenient but unofficial, so quality and capacity vary widely between brands using them. Reputable makers print the IEC code alongside the AG number on the cell itself. If a bargain pack shows only an AG code and no IEC marking at all, treat the capacity claims with suspicion, and keep such cells out of anything you care about, like a watch with a calendar complication that drains steadily for years.

Why does one battery have five names?

Layer the systems and the aliases pile up fast. The humble LR44 answers to LR44, LR1154, AG13, A76, and 1166A, and every one of those names describes an identical alkaline cell. Its silver oxide counterpart in the same case answers to SR44, SR44W, 357, SG13, and EPX76. Nothing about the battery changes. Only the catalog does.

The practical takeaway: when you replace a cell, match three things in order. Chemistry first, because voltage differs between alkaline and silver oxide. Dimensions second, because a 0.5 mm height difference can leave a contact floating. Drain rating last, for watches with alarms or lights. A cross reference lookup handles the translation for you, which is what the CellChart search is built to do.