You popped open a car key, a bathroom scale or a remote, found a flat silver disc inside, and now you are squinting at a tiny code trying to work out what to buy. The good news: once you understand how coin cells are numbered, picking the right one takes about ten seconds. This guide walks you through it, maps the common batteries to the devices that use them, and shows you how to check whether the old one is actually dead.
Everything below refers to CR-type lithium coin cells, which are 3V and by far the most common type in everyday gadgets. If your code starts with SR or LR instead, that is a different 1.5V button cell, and you will want our button-cell range instead.
The code tells you the size
A CR code is not random. It is the diameter and the thickness of the battery in millimetres:
CR2032 = CR (3V lithium) + 20 mm wide + 3.2 mm thick.
So the last two digits are the height in tenths of a millimetre. That single rule decodes every coin cell you are likely to meet:
| Battery | Diameter | Thickness | Rough capacity | Where you'll see it |
|---|---|---|---|---|
| CR2016 | 20 mm | 1.6 mm | ~90 mAh | Slim key fobs, light-up toys |
| CR2025 | 20 mm | 2.5 mm | ~165 mAh | Key fobs, some scales |
| CR2032 | 20 mm | 3.2 mm | ~225 mAh | The default: key fobs, remotes, scales, PC motherboards |
| CR2430 | 24.5 mm | 3.0 mm | ~290 mAh | Larger remotes, some medical devices |
| CR2450 | 24.5 mm | 5.0 mm | ~620 mAh | Car tyre pressure sensors (TPMS), access cards |
| CR2477 | 24.5 mm | 7.7 mm | ~1000 mAh | Long-life sensors, beacons, trackers |
Two families fall out of that table. The 20 mm group (CR2016, CR2025, CR2032) all share the same width and differ only in thickness. The 24.5 mm group (CR2430, CR2450, CR2477) is physically larger and holds a lot more charge.
Match the battery to your device
If you still have the old battery, just read the code off it. That is always the most reliable answer. If you cannot, here is what the common items in a Singapore household typically take:
- Car key fobs: usually CR2032, sometimes CR2025 or CR2016. Toyota, Honda, Mazda and Hyundai remotes are very often CR2032. Always confirm against the old cell, because trim levels vary.
- TV, set-top box and aircon remotes: most use AAA or AA, but slim or premium remotes use CR2025 or CR2032.
- Bathroom and kitchen scales: CR2032 is the standard.
- Heart-rate chest straps and fitness sensors: usually CR2032, occasionally CR2025.
- Tyre pressure sensors (TPMS): commonly CR2450 because of the higher capacity needed.
- PC and laptop motherboards (the CMOS clock battery): almost universally CR2032. If your desktop keeps forgetting the time and date, this is the fix.
- Glucometers and other home medical devices: frequently CR2032; check the manual.
Can I swap one size for another?
Short answer: only within reason, and only the 20 mm group.
Because CR2016, CR2025 and CR2032 are all 20 mm wide and all 3V, a device built for one will physically accept the others. But thickness matters. A thinner cell (say a CR2025 in a CR2032 holder) may sit loose, make poor contact and die sooner because it holds less charge. Going the other way, a CR2032 is often too thick for a CR2025 slot and can spring the holder or refuse to close.
The 24.5 mm cells are not interchangeable with the 20 mm ones, and within that group a CR2450 will not seat properly in a CR2430 housing. The safe habit: buy the exact code your device specifies. If you genuinely cannot find it and need to improvise, staying inside the 20 mm group is the only swap worth attempting, and only as a stopgap.
Does brand actually matter?
For something this cheap, yes, more than you would expect. A genuine cell from a known manufacturer gives you three things a no-name disc often does not: the rated capacity actually inside it, far better resistance to leaking (a leaking coin cell can corrode a key fob's contacts), and a low self-discharge rate so it still works after sitting in a drawer for years.
For everyday CR2032 needs, our CR2032 multi-pack is the value option, and we also stock genuine Panasonic CR2032 and Energizer CR2032 for brand-critical uses like car keys. For the larger sizes, the Toshiba CR2430 / CR2450, Panasonic CR2477 and the Swiss-made Renata CR2477N cover the high-capacity end. You can see the full range on the Coin Cell Batteries page.
How to tell if a coin cell is actually dead
Before you replace anything, it is worth confirming the battery is the problem. A fresh CR coin cell reads about 3.0 to 3.3V off the shelf. As it depletes, the resting voltage drops; once it sits below roughly 2.7 to 2.8V, the device will start misbehaving even though the battery is not at zero, and it is time to swap.
A multimeter on the DC volts setting will tell you the resting voltage, but resting voltage alone can be misleading because a tired cell can show a healthy reading until you put it under load. A dedicated tester checks it properly under load and has a slot sized for button cells. Our BT-168 battery tester handles coin cells alongside AA, AAA, C, D and 9V, needs no batteries of its own to run, and gives you an instant good or replace reading.
Where to buy coin cells in Singapore
We stock genuine CR2016 through CR2477 with fast local delivery, so you are not waiting on overseas shipping for a battery you need today. Browse everything on the Coin Cell Batteries collection, and if you are not sure which one you need, the device list above will get you there.
Frequently asked questions
Are all CR2032 batteries the same?
Electrically they are all 3V, 20 x 3.2 mm, so any CR2032 will fit any CR2032 device. The difference is in real capacity, leak resistance and shelf life, which is where a genuine branded cell earns its keep over a generic one.
Is CR2025 the same as CR2032?
Same width and voltage, but the CR2025 is thinner (2.5 mm vs 3.2 mm) and holds less charge. A CR2025 will usually fit a CR2032 slot but last less long and may sit loose; a CR2032 is often too thick to fit a CR2025 slot. Use the exact code your device asks for.
What is the difference between CR2430 and CR2450?
Both are 24.5 mm wide, but the CR2450 is 5.0 mm thick versus the CR2430's 3.0 mm, so the CR2450 holds roughly double the capacity. They are not interchangeable, the thicker one will not seat in the thinner housing.
How long does a coin cell last?
Unused, a lithium coin cell keeps for up to about ten years thanks to its very low self-discharge. In a device, life depends entirely on the draw, from a few months in a busy heart-rate sensor to several years in a motherboard clock.
Which battery is in a car key fob?
Most often a CR2032, with some models using CR2025 or CR2016. The only sure way is to open the fob and read the old cell, since it varies by make, model and year.