Does anyone know why the 15 MB card allowed only 11.5 MB of pics to be taken?

[Ivory1234]

(1) I inserted a 15 Mb SD card in my A530, (2) I took 5 pics of 2.3 MB, and (3) a message saying my memory card is full appeared.

(5 x 2.3 = 11.5 MB)

Does anyone know why the 15 MB card allowed only 11.5 MB of pics to be taken?

[Waddizzle]

Overhead for the Block Allocation Map.

[Ivory1234]

Thanks.