It depends on how much you print (of course). The heads are set for a max of 10,000,000 droplets before needing replaced (ink usage based), but there can be the defective issue as well. Average is probably around 1 1/2 years I would think. Since this is something about as difficult to calculate like how many prints you can get out of an ink set, that's my guess. I've heard some customers that didn't replace their head for about 2+ years, so that's the tricky question.