AA vs D
Both 1.5 V alkaline. At 34.2 × 61.5 mm against 14.5 × 50.5 mm, the D holds roughly six times the energy of an AA.
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Both give 1.5 volts. The D is much larger and holds around six times as much energy, so it runs far longer between changes — that is the entire difference. They are not interchangeable: a D is more than twice the width of an AA and a centimetre longer. Adapter sleeves let an AA sit in a D compartment, but you get AA runtime, not D runtime, and less current with it.
- Verdict:
- Same 1.5 V, roughly six times the runtime
- Interchangeable:
- no
Side-by-side specifications
| Specification | AA | D |
|---|---|---|
| Chemistry | Alkaline | Alkaline |
| Type | Cylindrical | Cylindrical |
| Nominal voltage | 1.5 V | 1.5 V |
| Diameter | 14.5 mm | 34.2 mm |
| Height | 50.5 mm | 61.5 mm |
| Typical capacity | 1800–2900 mAh | 12000–18000 mAh |
| Rechargeable | No | No |
| Also sold as | LR6, MN1500, AM3, R6 | LR20, MN1300, AM1, R20 |
Size comparison
These cells do not share a footprint, so one will not sit correctly in the other's compartment.
Size
34.2 × 61.5 mm against 14.5 × 50.5 mm. The D is the largest of the common household cells and does not share a compartment with anything else.
Runtime
12000–18000 mAh against 1800–2900 mAh — around six times the reserve, which is why lanterns and floor sweepers are built around it.
Current, not just capacity
A larger cell also sustains a higher current. Devices that specify D cells often need that, so an AA in an adapter can sag under load even where it physically works.
What D cells are actually for
Lanterns, large torches, floor sweepers and portable radios that must run for days. The choice is rarely about power delivery and almost always about how long the thing runs before someone has to open it, which is why D cells persist in equipment kept for emergencies.
The adapter caveat is bigger here
An AA in a D sleeve gives you a sixth of the capacity, and D-cell devices are usually the ones drawing real current. A lantern designed around D cells can dim visibly on adapted AAs, and a motorised device may not start at all. The sleeve is a stopgap, not a substitute.
Weight and shipping
A D cell weighs around 140 g against 23 g for an AA. In anything carried, that is the reason designers avoid them, and it is why most modern camping gear moved to AA or to built-in lithium packs even at the cost of runtime.
Can I use a D instead of an AA?
Not directly. The D measures 34.2 × 61.5 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 D: common questions
Is the D a direct replacement for the AA?
Both give 1.5 volts. The D is much larger and holds around six times as much energy, so it runs far longer between changes — that is the entire difference. They are not interchangeable: a D is more than twice the width of an AA and a centimetre longer. Adapter sleeves let an AA sit in a D compartment, but you get AA runtime, not D runtime, and less current with it.
What is the difference between the AA and the D?
Both 1.5 V alkaline. At 34.2 × 61.5 mm against 14.5 × 50.5 mm, the D holds roughly six times the energy of an AA. In short: same 1.5 V, roughly six times the runtime.
Are the AA and the D the same size?
No. The AA is 14.5 × 50.5 mm and the D is 34.2 × 61.5 mm.
Which lasts longer, the AA or the D?
The D. It is rated at 12000–18000 mAh against 1800–2900 mAh for the AA — roughly 6.4× 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