AA vs AAAA

Both 1.5 V alkaline, but the AAAA is 8.3 × 42.5 mm against 14.5 × 50.5 mm and holds about a quarter of the energy.

Quick answer

Both are 1.5 volts, and that is where the similarity ends. The AAAA is much thinner and shorter than an AA and holds roughly a quarter of the energy. Nothing built for an AA will take an AAAA — it is far too small to reach the contacts. Most people only ever meet an AAAA inside an active stylus or a slim penlight.

Verdict:: Not interchangeable — the AAAA is a quarter of the cell
Interchangeable:: no

Side-by-side specifications

AA compared with AAAA
Specification	AA	AAAA
Chemistry	Alkaline	Alkaline
Type	Cylindrical	Cylindrical
Nominal voltage	1.5 V	1.5 V
Diameter	14.5 mm	8.3 mm
Height	50.5 mm	42.5 mm
Typical capacity	1800–2900 mAh	500–650 mAh
Rechargeable	No	No
Also sold as	LR6, MN1500, AM3, R6	LR61, MN2500, MX2500, E96

Size comparison

Ø 14.5 mm · H 50.5 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

8.3 × 42.5 mm against 14.5 × 50.5 mm. The AAAA is not much over half the diameter of an AA, so it cannot bridge the contacts in an AA bay at all.

Runtime

500–650 mAh against 1800–2900 mAh, roughly a quarter. The AAAA is chosen when a product has no room, never when it needs endurance.

The 9 V rumour

Some alkaline 9 V blocks are built from six AAAA-sized cells, which is why guides circulate suggesting you open one to harvest them. Not every 9 V is built that way, and prising a battery apart risks shorting the cells and burning yourself. Buy the AAAA.

Can I use a AAAA instead of a AA?

Not directly. The AAAA measures 8.3 × 42.5 mm against 14.5 × 50.5 mm for the AA, so it will not seat properly in the same compartment.

AA 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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