“Subtracting this uninhabitable 57% (32,665,981 mi2) from the total land area leaves 24,642,757 square miles or 15.77 billion acres of habitable land. Divide this figure by the current human population of 7 billion (that’s 7,000 million people) and you get 2.3 acres (about one hectare) per person.” according to http://www.zo.utexas.edu/courses/Thoc/land.html#:~:text=Subtracting%20this%20uninhabitable%2057%25%20(32%2C665%2C981,about%20one%20hectare)%20per%20person.