I read a previous post that a user obtained 42 minutes of recording on a 32GB card @, I assume, 100Mbps.

The question I have is: how much ACTUAL space is available on a 32 (and 64)? Like hard drives, they never are their rated capacity.

I'd like to simply get a handle on the GB per minute (at various rates) which helps figure card needs, etc.

32GB = 42 min = approx. .7619GB/m

With the maximum clip size of 3.5GB, we're looking at a 4.59 minute clip.

Does this sound about right?

By knowing the NET CAPACITY of the card we can be more precise in this prediction.