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.

Quick answer

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

AA compared with C
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

Ø 14.5 mm · H 50.5 mm

Ø 26.2 mm · H 50 mm

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.

Can I use a C instead of a 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.

AA specs →C specs →

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.

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