AA vs C
Both 1.5 V alkaline cells. The C is 26.2 mm across against 14.5 mm and holds roughly three times the energy, though the two are within half a millimetre of the same length.
Last reviewed
Both give 1.5 volts, so neither is more powerful than the other in the way people expect. The C simply holds about three times as much, so it lasts about three times as long. They are not swappable — the C is nearly twice the width of an AA, even though the two are almost exactly the same length. Plastic adapter sleeves let an AA sit in a C compartment and they do work, but you only get AA runtime out of it.
- Verdict:
- Same voltage, about three times the runtime
- Interchangeable:
- no
Side-by-side specifications
| Specification | AA | C |
|---|---|---|
| Chemistry | Alkaline | Alkaline |
| Type | Cylindrical | Cylindrical |
| Nominal voltage | 1.5 V | 1.5 V |
| Diameter | 14.5 mm | 26.2 mm |
| Height | 50.5 mm | 50 mm |
| Typical capacity | 1800–2900 mAh | 6000–8000 mAh |
| Rechargeable | No | No |
| Also sold as | LR6, MN1500, AM3, R6 | LR14, MN1400, AM2, R14 |
Size comparison
These cells do not share a footprint, so one will not sit correctly in the other's compartment.
Same length, different width
50 mm against 50.5 mm — an AA and a C are practically identical end to end. Diameter is the whole difference: 26.2 mm against 14.5 mm.
Runtime, not power
6000–8000 mAh against 1800–2900 mAh. Both deliver 1.5 V. The C just carries roughly three times as much of it before it is spent.
Adapter sleeves
A hollow sleeve will hold an AA in a C bay, and because the voltage matches it works. You get the AA's capacity and the AA's lower current ceiling: fine for a clock or a radio, poor for anything with a motor.
Why the C size is fading
C cells occupy an awkward middle ground, and as devices became more efficient many products that once needed them moved to AA. The result is that C cells are harder to find and cost more per cell than the arithmetic suggests they should, which is worth factoring in before buying a device that takes them.
When an adapter is genuinely fine
A radio, a clock or an LED lantern draws little enough that an AA in a C sleeve behaves normally, just for a third as long. The place it fails is anything with a motor or a heating element, where the AA's higher internal resistance shows up as a device that runs weakly or cuts out under load.
Check the tray before buying an adapter
Sleeves rely on the compartment gripping the cell. In a spring-loaded tray they sit fine; in a tube where the cells stack end to end they can rotate and break contact. Cheap sleeves also vary in length, and one that leaves the AA short of the terminal is a common source of a device that seems dead.
Can I use a C instead of an AA?
Not directly. The C measures 26.2 × 50 mm against 14.5 × 50.5 mm for the AA, 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.
AA vs C: common questions
Is the C a direct replacement for the AA?
Both give 1.5 volts, so neither is more powerful than the other in the way people expect. The C simply holds about three times as much, so it lasts about three times as long. They are not swappable — the C is nearly twice the width of an AA, even though the two are almost exactly the same length. Plastic adapter sleeves let an AA sit in a C compartment and they do work, but you only get AA runtime out of it.
What is the difference between the AA and the C?
Both 1.5 V alkaline cells. The C is 26.2 mm across against 14.5 mm and holds roughly three times the energy, though the two are within half a millimetre of the same length. In short: same voltage, about three times the runtime.
Are the AA and the C the same size?
No. The AA is 14.5 × 50.5 mm and the C is 26.2 × 50 mm.
Which lasts longer, the AA or the C?
The C. It is rated at 6000–8000 mAh against 1800–2900 mAh for the AA — roughly 3.0× the capacity, though real runtime depends on how much current your device draws.
Background reading
The wider questions behind these two codes.
Lithium for cold, weight and high drain; alkaline for everything else
NiMH for anything you replace often, alkaline for anything you forget about
Switch anything you replace more than twice a year
Lithium for standby and extremes, NiMH for anything used often