AA vs AAA
AA (≈14.5 × 50.5 mm) and AAA (≈10.5 × 44.5 mm) are both common 1.5V alkaline sizes. Capacity and physical fit differ — adapters exist but reduce convenience and often capacity.
Last verified Aug 25, 2026
Not interchangeable. Match the size your device requires.
A AAA vs AA swap fails on diameter, thickness, capacity. If the door only closes when you force it, or the device works only while you press the cover, you have the wrong cell — not a weak spring you should ignore.
They share 1.5 V and Alkaline, which is why AA vs AAA looks interchangeable on a store shelf. Highlighted rows are the ones that change the purchase: diameter, thickness, capacity.
Read physical fit before capacity. Extra milliamp-hours only help when the holder is built for that cell. A “better” spec in the wrong tray is a mechanical or voltage mismatch, not an upgrade.
If you searched AAA vs AA, you are on the same comparison with the names reversed. The difference between AA and AAA batteries is not the word “vs” — it is the specs that do not match after you ignore the similar photos.
AA is 14.5 mm across; AAA is 10.5 mm. That gap is enough for one cell to miss the clip entirely or rattle in the other tray. IEC codes put diameter in the first digits for a reason: you cannot sand a coin cell down to fit.
AA is 50.5 mm thick; AAA is 44.5 mm. Holders are built for one stack height. The thinner cell loses spring pressure (“works only when I press the cover”). The thicker cell jams the door or bends the clip.
Typical AA capacity is 2000–3000 mAh. AAA is 1000–1200 mAh. Runtime only follows that gap inside the correct holder. Extra capacity in the wrong tray does not last longer — it often does not run at all.
AA is larger and typically 2000–3000 mAh alkaline; AAA roughly 1000–1200 mAh
NiMH rechargeables exist in both sizes at ~1.2V nominal
14500 / 10440 Li-ion look similar in size class but are ~3.7V — not alkaline AA/AAA
Coin and button codes are rulers, not brand slogans. The letters mark chemistry class. The digits encode size. AA measures 14.5 × 50.5 mm; AAA measures 10.5 × 44.5 mm. Once you read the code that way, AAA vs AA stops looking like a preference and starts looking like a fit check.
Usually no. AA is 14.5 × 50.5 mm at 1.5 V (Alkaline). AAA is 10.5 × 44.5 mm at 1.5 V (Alkaline). Those are not the same part.
If the spent cell or tray said AAA, specify that code. Forcing AA can crack a cover, lose contact, or apply the wrong voltage.
Usually no. Going the other way does not fix a diameter, thickness, or voltage miss. AAA in a AA holder has the same problem with the names flipped.
If you arrived from a AAA vs AA search, stay on this page. The answer does not change.
Retail packs hide the IEC size behind house codes. AA also appears as LR6, 15A, MIGNON. AAA also appears as LR03, 24A. Those prefixes do not change the outline unless the chemistry letters change (BR, LIR, ML, PR).
You do not need a full datasheet to settle AA vs AAA. You need the stamp, the tray, or a cheap pair of calipers. A store bin labeled only “button cell” or “3V lithium” will not do that work for you.
Spacer adapters that let AAA sit in AA tubes are a last resort for emergencies, not a design recommendation.
Do not stack cells, grind a can, or use foil as a permanent spacer to fake AAA with AA. Read the stamp, then the spec table. If the door will not close without force, you have the wrong height or diameter.
Sometimes mechanically, with much less capacity and possible contact issues. Prefer the correct size.
Yes. AA vs AAA and AAA vs AA are the same pair. Fit, voltage, and chemistry do not change when you flip the order.
Use this guide as a starting point, then confirm voltage, chemistry, and physical size with your device manual or the marking on the old cell.
Reviewed by PlainBattery Technical Review Desk on 2026-08-25. Checked: both model identities and dimensions, voltage and chemistry differences, physical fit, interchangeability conclusion and safety warnings.
Revision record: source citations and field-level review scope added September 11, 2026. See our sources and methodology and corrections policy.
