Index / LR44 / LR44 vs PR44

LR44 vs PR44: what differs, and which goes where

LR44 and PR44 share the same 11.6 x 5.4 mm envelope. LR44 is an alkaline cell at 1.5 V; PR44 is a zinc air cell at 1.45 V. PR44 in a holder built for LR44: needs air, at 1.45 V against 1.5 V. LR44 in a holder built for PR44: drop-in, at 1.5 V against 1.45 V.

Warning — button cell

LR44 is a button cell: 11.6 mm across and 5.4 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 LR44 and PR44; the last column is ours, the difference read off the printed tenths of a millimeter.

LR44 and PR44, published figures
Figure	LR44	PR44	Difference
Diameter	11.6 mm	11.6 mm	same
Height	5.4 mm	5.4 mm	same
Nominal voltage	1.5 V	1.45 V	close enough
Chemistry	alkaline	zinc air	different
Capacity	150 mAh	not published	—
Stored energy	225 mWh	not published	—
In the Energizer catalog	listed	listed	—
Sold as	LR44, AG13, A76, 76A, GP76A, 1166A	PR44, 675, ZA675, 7003ZD, AC675E	—

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. LR44 is 5.4 mm deep and PR44 is 5.4 mm.

PR44 in a holder built for LR44 — PR44 matches the size but is zinc air, so it works only where air reaches it: a hearing aid, not a sealed watch, caliper or toy; it runs 1.45 V against the 1.5 V the device expects, a few hundredths of a volt below, which almost nothing notices.
LR44 in a holder built for PR44 — LR44 matches the holder within 0.3 mm; it runs 1.5 V against the 1.45 V the device expects, a few hundredths of a volt above, which almost nothing notices.

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 PR44: both reach it.

This cellAnother cell, same scale

How long each one runs

Energizer publishes a capacity for only LR44, so a running time can be compared only from the other maker's sheet. LR44 holds 150 mAh at 1.5 V, about 225 milliwatt-hours.

What each one is made for

LR44 at 1.5 V is made for watches, calculators and small instruments that draw very little; PR44 at 1.45 V is made for hearing aids, where it starts running when the tab comes off. 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 (LR44, 1.5 V) drops in voltage steadily as it empties, so a device calibrated for a flat discharge will drift as it goes.
Zinc air (PR44, 1.45 V) takes oxygen from the air through the holes in its face. It starts discharging the moment the tab comes off and runs down in weeks whether the device is used or not, and a sealed compartment starves it.

What the codes and the sheets add

LR44 does not encode its size, so only the sheet says it; PR44 does not encode its size, so only the sheet says it. Beyond size and voltage, the sheets say this: LR44 weighs 2 g and PR44 weighs 1.9 g.

Telling them apart in the hand

The code is printed on the flat face of each: LR44 on one, PR44 on the other. On a caliper they read the same within 0.3 mm, so the printed code and the chemistry on the label are the only things that separate them. 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

LR44 also appears as 1166A and A76 in Energizer's own part numbers, and other brands sell it as AG13, A76 and 76A; PR44 also appears as 7003ZD and AC675E in Energizer's own part numbers, and other brands sell it as 675 and ZA675. 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, LR43 vs LR44.

Which one to buy

Buy the code printed on the old cell or named in the manual. PR44 stands in where LR44 sat only where air reaches it, at 1.45 V against 1.5 V. In a pinch LR44 can stand in where PR44 sat, at 1.5 V against 1.45 V. Both pages carry the full figures and sources: LR44 and PR44.

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.