18650 vs 14500

Both 3.6 V lithium-ion. The 18650 is 18 × 65 mm against the AA-sized 14 × 50 mm 14500, with three to four times the capacity.

Quick answer

Both are rechargeable lithium-ion cells at 3.6 volts, so electrically they behave alike. The 18650 is much larger and holds three to four times as much. They do not interchange: the 14500 is AA-sized, the 18650 considerably fatter and longer. Worth knowing that the 14500 is the one that fits an AA slot — and must never be used in one.

Verdict:: Same chemistry, entirely different size class
Interchangeable:: no

Side-by-side specifications

18650 compared with 14500
Specification	18650	14500
Chemistry	Li-ion	Li-ion
Type	Cylindrical	Cylindrical
Nominal voltage	3.6 V	3.6 V
Diameter	18 mm	14 mm
Height	65 mm	50 mm
Typical capacity	2000–3500 mAh	700–1000 mAh
Rechargeable	Yes	Yes
Also sold as	INR18650, ICR18650, NCR18650	ICR14500, IMR14500

Size comparison

18650

Ø 18 mm · H 65 mm

14500

Ø 14 mm · H 50 mm

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

Size

18 × 65 mm against 14 × 50 mm. The codes give the dimensions directly, so the gap is easy to read off the label.

Capacity

2000–3500 mAh against 700–1000 mAh. The 18650 carries three to four times the energy of the smaller cell.

The AA trap belongs to the 14500

Only the 14500 shares a footprint with a household cell. An 18650 will not fit an AA compartment; a 14500 will, and at 3.6 V it should never be put in one.

Can I use a 14500 instead of a 18650?

Not directly. The 14500 measures 14 × 50 mm against 18 × 65 mm for the 18650, so it will not seat properly in the same compartment.

18650 specs →14500 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.

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