CR2 vs CR123A
Both 3 V single-use lithium. The CR2 is 15.6 × 27 mm against the CR123A's 17 × 34.5 mm, with roughly half the capacity.
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Both are 3 volt single-use lithium cells, and neither is rechargeable — but they are not the same size. The CR2 is shorter and slightly narrower, and holds about half the energy of a CR123A. They do not interchange. Both turn up in cameras and sensors, so check the code printed on the cell you took out rather than going by appearance.
- Verdict:
- Both 3 V lithium, but the CR2 is much the smaller cell
- Interchangeable:
- no
Side-by-side specifications
| Specification | CR2 | CR123A |
|---|---|---|
| Chemistry | Lithium | Lithium |
| Type | Cylindrical | Cylindrical |
| Nominal voltage | 3 V | 3 V |
| Diameter | 15.6 mm | 17 mm |
| Height | 27 mm | 34.5 mm |
| Typical capacity | 750–850 mAh | 1400–1600 mAh |
| Rechargeable | No | No |
| Also sold as | CR15H270, DLCR2, EL1CR2, 5046LC | CR17345, DL123A, EL123A, 123 |
Size comparison
These cells do not share a footprint, so one will not sit correctly in the other's compartment.
Size
15.6 × 27 mm against 17 × 34.5 mm. The CR2 is noticeably stubbier — 7.5 mm shorter — and will not bridge the contacts in a CR123A compartment.
Capacity
750–850 mAh against 1400–1600 mAh. Roughly half, in a cell of roughly half the volume.
Same chemistry, same caution
Both are primary lithium at 3 V with long shelf lives, and neither may be recharged. Rechargeable look-alikes exist for both footprints and run at a higher voltage.
Both are camera-era cells
The CR2 and the CR123A came out of film photography, powering autofocus and motor drives when AAs were too bulky. That is why both turn up in older cameras, rangefinders and, later, in alarm sensors and bike lights that wanted the same long shelf life.
Rechargeable versions of each
The 16340 is the rechargeable in the CR123A footprint and a 15270 exists for the CR2, both at a higher voltage than the primary they resemble. The same caution applies to each: only use one where the device names it.
Availability differs
The CR123A is stocked widely because security equipment keeps demand up. The CR2 is a narrower market, often more expensive per cell and less likely to be on a supermarket shelf, which is worth knowing before buying a device that needs one.
Can I use a CR123A instead of a CR2?
Not directly. The CR123A measures 17 × 34.5 mm against 15.6 × 27 mm for the CR2, so it will not seat properly in the same compartment.
Check before you swap. Batteries with similar dimensions are not always interchangeable. Always verify voltage, chemistry and the requirements printed in your device manual before fitting a replacement.
CR2 vs CR123A: common questions
Is the CR123A a direct replacement for the CR2?
Both are 3 volt single-use lithium cells, and neither is rechargeable — but they are not the same size. The CR2 is shorter and slightly narrower, and holds about half the energy of a CR123A. They do not interchange. Both turn up in cameras and sensors, so check the code printed on the cell you took out rather than going by appearance.
What is the difference between the CR2 and the CR123A?
Both 3 V single-use lithium. The CR2 is 15.6 × 27 mm against the CR123A's 17 × 34.5 mm, with roughly half the capacity. In short: both 3 V lithium, but the CR2 is much the smaller cell.
Are the CR2 and the CR123A the same size?
No. The CR2 is 15.6 × 27 mm and the CR123A is 17 × 34.5 mm.
Which lasts longer, the CR2 or the CR123A?
The CR123A. It is rated at 1400–1600 mAh against 750–850 mAh for the CR2 — roughly 1.9× the capacity, though real runtime depends on how much current your device draws.
Background reading
The wider questions behind these two codes.