We discuss the reported capacities of available packed column ion exchange columns and the different methods used for their measurement. We outline basic considerations related to both packed and open tubular columns based on ion exchange latex particles. There is a large body of information covering the retention behavior of packed ion exchange columns based on ion exchange latex particles. We propose a parameter γiex, which is the ion exchange capacity of a column (packed or open tubular) per unit liquid volume present in the column (including accessible volume within pores) and show that the retention factor for any given ion is directly related to γiex. On this basis, if based on the same type of latex, the behavior of one type of column can be reasonably predicted from the known behavior of the other, even when the absolute capacities differ by more than 5 orders of magnitude.