I can get mine down to a 4" by 4" by 4" cube, but that puts a lot of corner stress on the material.  I prefer to blanket fold the thing into a 9" width by it's full length, then roll it tightly, wich doesn't create an corner stress.  It fits in a nice 3" diamter by 10" long stuff sack that way.  That's about as small as you can expect it to get without pinching the material down. 
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)