The Montgomery County jail sizing study was a projection analysis of expected jail population in the Washington D.C. suburb. The study projected the total population under control of Montgomery County criminal justice agencies through the year 2010. The projections were made using linear regression, based upon county population. Statistical analysis was used to eliminate a wide variety of economic and social indicators from the equations. The resulting statistical models projected jail intake and average daily population independently. Based upon the results of these statistical models, a spreadsheet model distributed the population under control into different correctional and pretrial alternatives as well as to the jail under specified conditions. The spreadsheet model allows county commissioners to vary the assumptions to see how jail and other alternative populations will be affected. The spreadsheet model can be recalibrated with new population and jail data as it becomes available in coming years. Based upon the projections, the county plans on building a much smaller jail with savings of over $200 million in capital costs and substantial operational savings.