Index / LR43 / LR43 vs LR44

LR43 vs LR44: what differs, and which goes where

LR43 and LR44 share the same 11.6 mm diameter, 4.2 mm against 5.4 mm deep. LR43 is an alkaline cell at 1.5 V; LR44 is an alkaline cell at 1.5 V. LR44 in a holder built for LR43: too tall, at 1.5 V against 1.5 V. LR43 in a holder built for LR44: sits lower, at 1.5 V against 1.5 V.

Warning — button cell

LR43 is a button cell: 11.6 mm across and 4.2 mm tall. If one has been swallowed, or put in a nose or an ear, call the United States national Poison Help line at 1-800-222-1222 straight away and do not wait for symptoms.

Why this shape is dangerous, and the law behind the pack

United States law defines that class by the shape alone — a single cell battery with a diameter greater than its height, 16 CFR 1263.2 — and not by what is inside it. Swallowed, a cell this shape can lodge instead of passing, and it is the current, not the metal, that does the damage.

At 11.6 mm and 1.5 V it is under the 16 mm diameter that lodges most readily — which makes it easier to swallow, not safer. The same current runs for as long as it sits.
Reese's Law (15 U.S.C. 2056e) and 16 CFR part 1263 put child-resistant packaging and a warning label on this class; packages manufactured or imported after 21 September 2024 carry it. That is why the pack is hard to open.
The same rule says what to do with the used cell, in its own words: dispose of it at once, keep it away from children, and do NOT put it in household trash (16 CFR 1263.4(b)(3)). Tape over both faces first — a cell too flat to run a watch still has enough left to burn.

Side by side

Every figure below is published by the maker for LR43 and LR44; the last column is ours, the difference read off the printed tenths of a millimeter.

LR43 and LR44, published figures
Figure	LR43	LR44	Difference
Diameter	11.6 mm	11.6 mm	same
Height	4.2 mm	5.4 mm	+1.2 mm
Nominal voltage	1.5 V	1.5 V	same
Chemistry	alkaline	alkaline	same
Capacity	113 mAh	150 mAh	—
Stored energy	170 mWh	225 mWh	—
In the Energizer catalog	listed	listed	—
Sold as	LR43, AG12, 186	LR44, AG13, A76, 76A, GP76A, 1166A	—

Either way round

Fit and voltage are separate answers, and they change with direction: the holder is built for one cell, and the other has to live with it. LR43 is 4.2 mm deep and LR44 is 5.4 mm.

LR44 in a holder built for LR43 — LR44 stands 1.2 mm taller and stops the cover closing; it runs 1.5 V against the 1.5 V the device expects, the same working voltage.
LR43 in a holder built for LR44 — LR43 goes in and stands 1.2 mm lower, so a spring contact may reach it and a flat tab will not; it runs 1.5 V against the 1.5 V the device expects, the same working voltage.

From BatteryCrossEvery designation in one pageEach code with what it measures and what it replaces

Drawn to scale

Both at one scale. The dashed line marks the height of LR44: LR43 stops 1.2 mm short of it.

This cellAnother cell, same scale

How long each one runs

LR43 holds 113 mAh at 1.5 V, about 170 milliwatt-hours; LR44 holds 150 mAh, about 225. In the same device LR44 runs noticeably longer, 1.3 times, which is the whole reason the bigger cell exists. Price follows less closely than energy does. Per cubic centimeter LR43 packs 424 milliwatt-hours against 395 for LR44, so the difference is construction, not only size.

What each one is made for

Both are made for watches, calculators and small instruments that draw very little, which is why they end up in the same drawer and get mixed up: LR43 at 1.5 V and LR44 at 1.5 V. Read the code off the old cell before buying: the device was designed around that one, and the drawing above is how the other one sits in it.

Alkaline (LR43, 1.5 V) drops in voltage steadily as it empties, so a device calibrated for a flat discharge will drift as it goes.

What the codes and the sheets add

LR43 does not encode its size, so only the sheet says it; LR44 does not encode its size, so only the sheet says it. Beyond size and voltage, the sheets say this: LR43 weighs 1.5 g and LR44 weighs 2 g.

Telling them apart in the hand

The code is printed on the flat face of each: LR43 on one, LR44 on the other. Stood side by side, LR44 is 1.2 mm deeper, about 1.29 times the height of LR43, which a caliper reads at once and a ruler barely shows. If the old cell is gone and the code with it, measure the holder instead: its depth and its opening are what this page compares.

Names on the package

LR43 also appears as 186 in Energizer's own part numbers, and other brands sell it as AG12; LR44 also appears as 1166A and A76 in Energizer's own part numbers, and other brands sell it as AG13, A76 and 76A. Energizer lists both, which says what is on the shelf under these numbers and nothing about who else still makes them.

Other comparisons: LR44 vs 357, LR44 vs 675.

Which one to buy

Buy the code printed on the old cell or named in the manual. In a pinch LR43 can stand in where LR44 sat, at 1.5 V against 1.5 V. Both pages carry the full figures and sources: LR43 and LR44.

Before you swap anything

Everything here is computed from published dimensions and nominal voltages. That answers whether a cell enters the compartment and whether the voltage matches on paper. It does not answer what your device does with the difference, and it cannot: a cell that fits can still be the wrong cell.

One more limit, and it is the biggest. This site reads a single manufacturer’s catalog. When a page says a designation is not listed, that means Energizer no longer offers a part under it — not that nobody makes the cell. Other makers may still sell it, and for common sizes they usually do.

A voltage difference is one relation between two cells, and this page prints it from the cell it is about — in every table on the page, including the one listing cells no longer made. A figure always belongs to the cell whose voltage is printed beside it: a cell that runs lower than this one carries a minus here, one that runs higher carries a plus, and two cells at the same nominal voltage carry zero. Meet the same pair on the other cell’s page and the sign is the other one, with the figure taken against that cell instead of this one; where the two run at the same voltage, both pages print zero. The class beside the figure is not read off that figure directly. It is decided on the gap itself, taken against the higher of the two nominal voltages, so one pair of cells gets one class whichever page you meet it on: counted from this side the boundary of the class that still runs falls at 20.0% below and 25.0% above, which is the same gap divided once by the larger nominal and once by the smaller. What genuinely differs between the two directions is the consequence, and the words carry it: a cell that runs low makes a calibrated instrument read below true, and a cell that runs high makes it read above.

3 things this site cannot see. Whether the contacts reach a shorter cell. Whether the device was calibrated for a chemistry that holds its voltage flat, which silver oxide does and alkaline does not. Whether the equipment tolerates the higher current a different chemistry can deliver. Rechargeable cells are never a drop-in for primary cells regardless of size.

Where these numbers come from

Dimensions, voltages, chemistries and capacities are published by the manufacturer and reproduced without change. Everything else on the page is ours, computed from those figures: whether one cell fits where another sat, how far apart their voltages are, stored energy and energy per cubic centimeter, the rank within a shell, and the check of the designation against the measured size.

Fit is decided within 0.3 mm on every axis, which is the order of a contact spring's travel. Voltage classes are decided by consequence, not by roundness, and they are decided on the gap between two nominal voltages taken against the higher of the two: 2.0% or less of it is the same working voltage, 6.0% starts to matter to a calibrated instrument, and past 20.0% it is a different class altogether. Measuring the gap against the higher figure is what makes the verdict the same from either cell’s page, while the printed percentage stays counted from the cell you are reading about. Cells with identical stored energy share a rank instead of being ordered arbitrarily.

Ranking uses capacity times nominal voltage, because capacity alone is not comparable across chemistries: 150 mAh at 3 V is twice the energy of 150 mAh at 1.5 V. Neighbors are chosen by measurement and never alphabetically, because two cells filed next to each other by name usually have nothing in common. A blank in any table means the maker publishes no figure, which is not the same as zero.

Source: Energizer technical data, retrieved 1 September 2026.