Originally Posted by weims
I wouldn't let that worry me too much. I believe that "how much" could be a somewhat subjective thing - depending on how "heavy" you color, etc., individual mileage would most likely vary.
I appreciate what you are saying, however, for me it is part of the Copic comparison. Copic has stated in the past how much ink is in its Ciao, Sketch, Original Markers, which in turn also lets the user know how many refills they will get out of a purchased refill.
As a secondary concern is usage. However, if I'm only getting a half full pen to begin with, I think I have the right to know that as well.