Battery Identification by Size and Shape

A free tool for naming a loose, unmarked battery from its dimensions. Many codes are dimensional: a CR2032 is a lithium coin 20 mm across and 3.2 mm thick, an 18650 is a li-ion cell 18 mm by 65 mm, and an LR6 is simply the IEC name for an AA. Measure the diameter and the length or height on a calibrated rule or printed circles, and the tool returns the everyday name with its IEC and ANSI equivalents.

Identifying a battery step by step

1
Measure the diameter

For a round cell, read the width across the face; for a coin cell, drop it onto the printed circles and find the one it fills.

2
Measure the length or height

Stand a cylindrical cell against the length scale, or read a coin cell on edge for its thickness — the figure that separates look-alikes.

3
Note the shape

A tall cylinder, a flat coin or a rectangular block with snap terminals each narrows the candidates before the numbers confirm it.

4
Read the codes

The tool matches both dimensions to a standard cell and shows the common name with its IEC and ANSI codes, chemistry and nominal voltage.

Read the IEC/ANSI code hidden in a battery's size

What this gauge does

Common, IEC and ANSI names
Returns the familiar label and the standard codes beside it — AA as LR6 / 15A, 9V as 6LR61 / 1604A — so a battery marked only with a code is still recognisable.
Decodes the number itself
Explains size codes where the digits are the dimensions: CR2032 means 20 mm wide, 3.2 mm high, and 18650 means 18 mm by 65.0 mm.
Cylindrical and coin cells
Covers AA, AAA, C, D and 9V, li-ion 18650, 21700 and CR123A, and the coin and button range from CR2032 to LR44 and SR-series watch cells.
Resolves the 20 mm coin trap
CR2032, CR2025 and CR2016 share a 20 mm face and differ only in thickness, so the tool leans on the height reading to separate them.
Chemistry from the letters
Reads the prefix — LR alkaline, CR lithium, SR silver-oxide — and pairs it with a nominal voltage so a replacement matches both size and chemistry.

Why the size code is worth decoding

A device that has eaten its battery rarely tells you what it took, and the spent cell may be marked only with a cryptic code or nothing at all. Because most battery names are built from the cell's own dimensions, the size is the identification. This tool reads diameter and height, decodes the number, and gives the common, IEC and ANSI names with chemistry and voltage — so you order an exact replacement instead of buying three packs to find the one that fits.

Battery identification questions

What do the numbers in a code like CR2032 mean?

For coin cells the digits are the size in millimetres. CR2032 is a lithium (CR) coin 20 mm in diameter and 3.2 mm thick; CR2016 is the same 20 mm face but 1.6 mm thick. Read the diameter and thickness and the code reads straight off them.

What is the difference between names like AA and LR6?

They are the same battery under different naming systems. "AA" is the common name, "LR6" is the IEC code for the alkaline version, and "15A" is the ANSI code. The tool shows all three so a cell marked only with a code is still identifiable.

Why is the thickness so important on a coin cell?

Because the popular 20 mm coins — CR2032, CR2025 and CR2016 — have an identical face and differ only in height (3.2, 2.5 and 1.6 mm). A thinner one may rattle or lose contact, and a thicker one will not fit, so the height is the deciding measurement.

Do the prefix letters tell me the chemistry?

Largely, yes. LR is an alkaline cell at about 1.5 V, CR is lithium at about 3 V, and SR is silver-oxide at about 1.55 V, common in watches. The tool reports the chemistry and nominal voltage so you do not swap a 3 V lithium coin for a 1.5 V alkaline of the same size.

Can it identify rechargeable cells like 18650?

Yes. Li-ion cells follow the same dimensional naming: 18650 is 18 mm in diameter and 65.0 mm long, and 21700 is 21 mm by 70 mm. Measure diameter and length and the tool names them just as it does disposable cells, though their voltage and charging differ.

My battery sits between two sizes — what should I assume?

Trust the shape and the closer dimension, and re-measure the height for coins or the length for cylinders, as that is usually where look-alikes split. Standard cells are made to tight tolerances, so a true reading lands on one size; a borderline result generally means a slightly worn or swollen cell.

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Who is this tool for?
🔌 Electronics Enthusiasts
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