Global food supply: Do we have enough?

50 million square kilometers of farmed land globally.
500,000,000,000,000 square feet.
Let’s imagine each square ft only grows 1/4 lb of vegetables per square feet years. (Not too hard, I think even I can do it.)
That is 125,000,000,000,000 lb of vegetables per year.
Devide by say 10 billion global population (now at 7.7 B);

12500 lb of vegetable per person per year!

Yup we have enough food!!


Say all I have is my house lot.
Lets assume a person need 3lb of vegetables per day or ~1000lb per year.
My house lot is 6000 sq ft; let’s say after house and etc., 2000 sq ft (say 40x50 garden) left to grow.  So whether or not I can feed a family of 4 depends on if I can achieve a yield of 2lb per sq ft.  Still does not seem that much but never tried before.