Just how expensive are the prisons? What is the cost of keeping an inmate in prison? How much do non-offenders or those who offend but are not imprisoned pay to maintain those who are? The answers to these important questions often remain elusive and in the full sense of costs and benefits there will be difficulties in quantifying a great many of the factors. In Australia there has been very little research into prison expenditure, either within a particular jurisdiction or between jurisdictions; there is a time gap between expenditure and publication which dates the material by the time it appears and there are geographical differences which affect the analysis. what follows is an attempt to bring earlier work a little closer to the present.