title_body: How many plants are needed to brew a cup of coffee?
upvoted_answer: It all boils down to three questions:
  1) Yield = How much did you get from the grounds?
  2) Strength = How much ended up in the cup?
  3) Ratio = What did you get there?
  
  Yield: Yield pertains to how much soluble you took from the coffee grounds. Ground coffee has something between 27-30% of its mass being soluble, that is, stuff you can dissolve in water. If you kept boiling and boiling coffee grounds in water, eventually you’d get everything that the grounds have to give. Above 22-24%, however, and you’ve essentially reached too far or squeezed too hard, because unpleasant flavors will emerge. Below 18%, and you’re not getting enough out of the coffee, at worst, leaving the coffee with underdeveloped flavors or simply wasting coffee. So it sort of answers the question, “How much did you get from the grounds?”
  
  Strength: Pertains to how much of the final brew is coffee, and how much is water. SCAA Golden Cup says 1.15-1.35% brew strength is a desirable zone to the most number of people, though we espresso-lovers tend to like a bit more… something like 1.3-1.5% brew strength. Over 1.5, up to 2.0% or more, and you’re in the “heavy, thick” coffee zone. Simply put,“How much ended up in the cup?”
  
  Ratio: Simply, grams per liter. It provides one of the major answers to the question that Yield and Strength might ask, that is, “How did you get there?” Perhaps the most easy-to-remember ratio is 60g/L, or 60 grams of coffee for every one liter of water. The fact that you can make a balanced, pleasing, delicious cup of coffee at 60 g/L should give any barista pause when they’re finding that they’re using 80 grams or more per liter when they’re making coffee. Is it “wrong” to make coffee at 90 g/L? No… but is the additional 50% of coffee yielding an additional 50% of coffee quality, compared to the barista down the street making superb coffee at 60 g/L?
  
  For the assistance of common men like me,
  
  
  Then, to clarify the actual number, if Arabica then 1 - 1.5 pounds per cycle and if Robusta 2 - 2.75 pounds. And then you can calculate the rest. ;)
  
  Sourced from http://portafilter.net.