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.
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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
| 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
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.
Why anyone meets a AAAA at all
Almost always through a stylus. The Surface Pen and several other active styluses run on one, as do slim laser pointers and some glucose meters. Outside those, it is a size most people go a lifetime without buying.
Buying one is the hard part
Supermarkets rarely stock AAAA, and when they do it costs several times an AA. Stationers and online are the reliable sources. Because turnover is low, checking the date on the pack matters more here than for a size that sells constantly.
No adapter helps
There is no sleeve that turns a AAAA into an AA — the shortfall is 6 mm of diameter and 8 of length, and the cell would have nothing to brace against. This is one of the few household size pairs with no workaround at all.
Can I use an AAAA instead of an 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.
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 AAAA: common questions
Is the AAAA a direct replacement for the AA?
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.
What is the difference between the AA and the 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. In short: not interchangeable — the AAAA is a quarter of the cell.
Are the AA and the AAAA the same size?
No. The AA is 14.5 × 50.5 mm and the AAAA is 8.3 × 42.5 mm.
Which lasts longer, the AA or the AAAA?
The AA. It is rated at 1800–2900 mAh against 500–650 mAh for the AAAA — roughly 4.1× 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