The usual assumption of plug flow of gas and liquid in packed columns may not be correct in many instances. If there is departure from this ideal flow case, then the driving force for mass transfer is diminished, and allowance must be made for additional packed height if the specified separation is to be made. On the basis of our earlier experimental work, we present here the methodology for making the nonideal flow correction and show examples of how the correction can have a significant impact on the separating capability of the contactor. In particular, newer high-efficiency packings are included in the study, specifically "through-flow" rings and strucured packings of both the gauze and sheet-metal types.