CR2032 vs CR2025 Key Fob Battery: Differences & Can You Swap Them?

The short answer: CR2032 and CR2025 are the same width and the same voltage, but a CR2032 is thicker and holds more energy. Both are 3-volt lithium coin cells about 20 mm across. The CR2032 is roughly 3.2 mm thick; the CR2025 is roughly 2.5 mm thick. That 0.7 mm difference is why the two are not truly interchangeable in a key fob, even though they look almost identical.

CR2032 vs CR2025: side-by-side specs

These figures come from the manufacturer datasheets (Energizer CR2032 and Energizer CR2025). Other brands are close, but not always identical.

In plain terms, the CR2025 holds roughly 28% less energy than the CR2032. In a key fob that mostly sleeps and wakes for a moment when you press a button, less capacity means it can run flat sooner.

What the numbers in the name mean

Lithium coin cells follow a simple naming rule, so you can read a battery code without looking anything up:

• CR means a lithium manganese dioxide cell with a round (coin) shape.
• The first two digits are the diameter in millimetres. In 2032 and 2025, the “20” means 20 mm.
• The last two digits are the thickness in tenths of a millimetre. “32” is 3.2 mm and “25” is 2.5 mm.

The same rule explains other sizes you may run into: a CR1620 is 16 mm wide and 2.0 mm thick, and a CR2016 is 20 mm wide and 1.6 mm thick. If you are not sure which size your fob uses, the key fob battery size chart lists common types.

Can you use a CR2025 instead of a CR2032 in a key fob?

Sometimes it will work, but it is not recommended as a long-term answer. Here is what usually happens in each direction.

CR2025 in a slot made for a CR2032

The cell is thinner, so the battery holder may not press firmly on both sides. The fob can still switch on, but a loose contact causes the problems people describe as “it works, then it doesn’t”: a short range, buttons that only respond on the second press, or a fob that cuts out when you bump it. Even with a good contact, you also start with less capacity, so expect a shorter life.

CR2032 in a slot made for a CR2025

The cell is 0.7 mm thicker than the compartment was designed for. The case may not close fully, the contacts can bend, and forcing the shell shut can crack the plastic or damage the circuit board. If the cover does not close without pressure, take the battery out and do not force it.

The safe rule is simple: match the code printed on the old battery. If you are away from home and only have the other size, use it to get through the day, then buy the right one.

How to check which battery your fob needs

1. Read the old battery. The code (CR2032 or CR2025) is stamped on the flat top face, the side marked with the + sign.
2. Check the owner’s manual. It lists the battery type, and often the exact opening method.
3. Look inside the fob case. Many fobs have the code moulded into the plastic near the battery holder.
4. Compare the thickness. If you have both sizes, hold each next to the old cell. A visible difference in thickness tells you which one it is.

Not sure how to get the case open without scratching it? Our guide on how to open a key fob to replace the battery covers the usual snap, screw and slot designs.

Replacing the battery: the short version

1. Open the fob using the slot, small screw or release button for your model.
2. Note which way the old battery faces. Most fobs have the + side facing up, but not all do. Take a photo before you remove it, or check our battery polarity guide.
3. Slide the old cell out with a plastic or wooden tool rather than metal, to avoid shorting or scratching the contacts.
4. Insert the new battery the same way round, handling it by the edges.
5. Close the case, then test every button near the car.

For step-by-step help with each size, see the CR2032 replacement guide and the CR2025 replacement guide. If you would rather do it yourself with confidence first, read can I replace a key fob battery myself?

Which one lasts longer in a key fob?

The CR2032 generally lasts longer because it stores more energy in the same footprint. How long either one lasts in practice depends on how often you press the buttons, whether the fob has keyless entry that keeps listening for the car, and the temperature. Many owners get somewhere between one and a few years, but there is no single number that fits every vehicle. We go into the details in how long key fob batteries last.

Signs your key fob battery is getting weak

A coin cell rarely dies without warning. Before it quits, you will often notice one or more of these:

• You have to stand closer to the car for the buttons to work.
• You need to press a button two or three times before the car responds.
• The fob works some days and not others, especially in cold weather.
• A “key fob battery low” message appears on the dashboard (on cars that have one).
• The small LED on the fob, if it has one, is dim or does not light.

Cold lowers the available power of any battery, which is why a borderline cell often fails on the first frosty morning. If you see these signs, replace the battery now rather than waiting to be locked out. Our guide to how often to replace a key fob battery explains a sensible schedule.

Common mistakes when swapping coin batteries

• Guessing the size from memory. Two fobs from the same brand can take different batteries. Always read the old cell.
• Touching the flat faces with bare fingers. Skin oils can add resistance at the contact. Hold the cell by the edges, and wipe it with a clean dry cloth if needed.
• Using metal tools to pry out the old battery. A screwdriver can short the cell, scratch the board or bend the contact tabs. A plastic spudger or a wooden toothpick is safer.
• Inserting the new battery upside down. It will look fine, but the fob will not work. Check the + side before you close the case.
• Stacking two thin cells to make up thickness. This is unsafe and unreliable. Use the single battery the fob was designed for.
• Leaving the old battery lying around. Dispose of it right away, out of reach of children.

Storing and disposing of spare coin batteries

Store spare cells in their original packaging, at room temperature and away from metal objects such as keys or coins, which can touch both faces and drain the battery. Keep them in a place children cannot reach. When a battery is finished, do not throw it in the household bin loose; many shops, electronics retailers and local recycling centres accept used lithium coin cells. Taping over both faces of the old cell with clear tape before you dispose of it is a simple extra precaution.

Tips for buying the right battery

• Buy from a seller that turns over stock quickly. Lithium cells have a long shelf life, but fresh ones are still the safer choice.
• Choose a known brand. Unbranded cells often have lower real capacity than the label claims.
• Skip any cell with a torn wrapper, dents, or signs of leaking, and never use one that looks swollen.
• Buy a two-pack and keep the spare in a drawer, not in the car.

If you want a shortlist, we compare popular options in our best CR2032 batteries for key fobs guide. You can also browse CR2032 batteries on Amazon or CR2025 batteries on Amazon. As an Amazon Associate, ReplaceKeyFob earns from qualifying purchases; see our disclaimer for details.

If the new battery does not fix it

If your fob still does not work after a fresh, correct battery, the cause is usually a contact that is dirty or bent, a battery inserted upside down, or a fob that has lost its pairing. Start with key fob not working after a battery replacement, and if you suspect pairing, read whether a key fob needs reprogramming after a battery change.

Frequently asked questions

Is a CR2032 the same as a CR2025?

No. They share the same voltage (3 V) and diameter (20 mm), but a CR2032 is about 3.2 mm thick and a CR2025 is about 2.5 mm thick, and the CR2032 has more capacity.

Which is thicker, CR2032 or CR2025?

The CR2032. The last two digits of the code give the thickness in tenths of a millimetre, so 32 means 3.2 mm and 25 means 2.5 mm.

Can I use a CR2032 instead of a CR2025?

Only if the case closes easily without pressure. In many fobs the extra thickness will not fit. Do not force the cover.

Can I use a CR2025 instead of a CR2032?

It may fit and work briefly, but the contact can be loose and the battery will not last as long. Use it as a temporary fix at most.

Do CR2032 and CR2025 have the same voltage?

Yes, both are nominally 3 volts.

Which battery does my car key fob use?

Check the code on the old battery, the owner’s manual, or the fob case. Many fobs use a CR2032, but CR2025, CR2016 and other sizes are common too, so confirm before you buy.

Do I need to reprogram my fob after changing the battery?

Usually not. Most fobs keep their pairing in non-volatile memory. If it stops working after a battery change, check the battery orientation and contacts first.

Bottom line

CR2032 and CR2025 are close cousins, not twins. Same width, same voltage, but the CR2032 is thicker and lasts longer. Always match the number on your old battery, keep a spare, and keep every coin cell out of children’s reach.