C vs D

Both 1.5 V alkaline. The D is 34.2 × 61.5 mm against the C's 26.2 × 50 mm, and holds roughly double the energy.

Quick answer

Both are 1.5 volts. The D is bigger and holds about twice as much, so it runs roughly twice as long. Neither fits the other's compartment — the D is 8 mm wider and over a centimetre longer. There is no performance decision to make here beyond size: fit whichever your device was built for.

Verdict:: D for double the runtime, C where a D will not fit
Interchangeable:: no

Side-by-side specifications

C compared with D
Specification	C	D
Chemistry	Alkaline	Alkaline
Type	Cylindrical	Cylindrical
Nominal voltage	1.5 V	1.5 V
Diameter	26.2 mm	34.2 mm
Height	50 mm	61.5 mm
Typical capacity	6000–8000 mAh	12000–18000 mAh
Rechargeable	No	No
Also sold as	LR14, MN1400, AM2, R14	LR20, MN1300, AM1, R20

Size comparison

Ø 26.2 mm · H 50 mm

Ø 34.2 mm · H 61.5 mm

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 26.2 × 50 mm. Eight millimetres of diameter and over ten of length — no adapter bridges this pair in the useful direction.

Runtime

12000–18000 mAh against 6000–8000 mAh. Roughly double, for a cell that takes up roughly double the space.

Where each turns up

D cells go into lanterns, large torches and anything left running for hours. C cells appear where a designer wanted more than an AA but did not have room for a D.

Can I use a D instead of a C?

Not directly. The D measures 34.2 × 61.5 mm against 26.2 × 50 mm for the C, so it will not seat properly in the same compartment.

C specs →D 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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