the Gusseted Cinchpack, just look up the dimensions:
e.g. 15" x 17" x 6" = 1530 cu. inches = 25 liters
I'd guess that actual volume is a bit less than that, because you can't fill it completely up as a rectangular cube, and this is probably somewhat less in capacity than a Smart Alec -- so, say 23.5 liters or so?
A large Cafe Bag is 12" x 13" x 3" for a quoted capacity of 11 liters. It's not mean to balloon out (only 3"
You can probably do the calculations for any of the bags you examine in detail for more precise dimenstions. After all, you know which of those bags you're thinking of, and that will probably give you a better answer than having one of us click randomly for dimensions to do a calculation.