How can I determine the block size of the filesystem on my Android?

I'm creating a bunch of flash cards for use with AnkiDroid and many of them contain images or sound files.

I would like to find a balance between image/audio file size, and clarity, without wasting a ton of space with files that exceed a block boundary by just a few bytes.

So I'd like to know how to determine the filesystem block size on any given android device. Is there an easy way to do this?