# opportunity cost when inside production possibility frontier

I am a bit confused about whether there is a opportunity cost moving from within the PPF to be closer to the PPF and use some of the unemployed resources.

I current thinking is that there is zero opportunity cost of using unemployed resources to produce more of one good because the alternative is that these resources will not be used and hence no wants or needs will be satisfied. Does my reasoning work? Or is the opportunity cost the used resources? Of units of the second that can no longer be produced?

• Let's say you decide to produce butter using those currently unemployed resources, couldn't those same resources be used to produce bread in place of the butter. Therefore, I figure there is an opportunity cost as various items can be produced but only a limited can actually be produced. – Sahaj Jan 27 at 8:44

In order to get rid of opportunity cost you would have to get rid of all other options and have just one single use to which all resources can be allocated (which would be just a straight line overlapping either $$y$$-axis or $$x$$-axis). But such PPFs are not used because resources virtually always have alternative uses. In fact a proper PPF that goes beyond didactic purposes would even have more than just two dimensions, one for each good, as factors (i.e. labor, capital etc.) can be alternatively used in various production processes not just two.