Calderwood has some transfer funds at his disposal but knows that he has inherited a large squad, many of whom were signed for big money by League One standards.
He said: "There will probably be one or two players who want to leave as the season develops, because they are not getting the chance.
"The nature of the game is that the squad will reduce before it increases.
"We have enough to start the season - it is whether we have enough in terms of strength in depth as the season develops.
"It may be that, at some point, if the right player becomes available, then I talk to the chairman about it.
"But in reality, we have almost three teams here. Ideally, that will come down, but we will make sure they all have an opportunity."