AAA vs AAAA

Both 1.5 V alkaline. The AAAA is 8.3 × 42.5 mm against the AAA's 10.5 × 44.5 mm, with roughly half the capacity.

Quick answer

Easy to confuse on paper, impossible to confuse in the hand. Both give 1.5 volts, but the AAAA is thinner and a little shorter than an AAA and holds around half the energy. They do not interchange. Count the A's in what your device asks for before you order — that really is the whole difference.

Verdict:: One letter apart in the name, about half the cell
Interchangeable:: no

Side-by-side specifications

AAA compared with AAAA
Specification	AAA	AAAA
Chemistry	Alkaline	Alkaline
Type	Cylindrical	Cylindrical
Nominal voltage	1.5 V	1.5 V
Diameter	10.5 mm	8.3 mm
Height	44.5 mm	42.5 mm
Typical capacity	850–1200 mAh	500–650 mAh
Rechargeable	No	No
Also sold as	LR03, MN2400, AM4, R03	LR61, MN2500, MX2500, E96

Size comparison

AAA

Ø 10.5 mm · H 44.5 mm

AAAA

Ø 8.3 mm · H 42.5 mm

These cells do not share a footprint, so one will not sit correctly in the other's compartment.

Size

10.5 × 44.5 mm against 8.3 × 42.5 mm. Only 2 mm separates them in length, but the AAAA is a fifth narrower — enough that it rattles loose in an AAA holder.

Runtime

850–1200 mAh against 500–650 mAh. The AAA runs roughly 80% longer in the same device.

Where you meet an AAAA

Active styluses, laser pointers, glucose meters and slim LED lights. It is a niche size, so it is usually dearer per cell and harder to find on a shelf than an AAA.

Can I use a AAAA instead of a AAA?

Not directly. The AAAA measures 8.3 × 42.5 mm against 10.5 × 44.5 mm for the AAA, so it will not seat properly in the same compartment.

AAA specs →AAAA 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.

Related comparisons

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