Traditionally, maldistribution of liquid and vapour flow in a packed column has been reported using the coefficient of variation or the ratio of maximum to minimum superficial velocity in the packing. While these provide some useful insight into the level of maldistribution introduced to a bed by the liquid distributors and vapour feeds, they are not necessarily good indicators of the depth of penetration of the maldistribution into the bed or its impact on column performance. Liquid maldistribution is characterized by both small length scale effects due to the discrete drip point locations as well as large length scale effects due to flow variations from drip point to drip point or across the distributor. Vapour flow, being more continuous in nature, does not have the small scale maldistributions of the liquid but does experience large scale effects due to geometry and location of the vapour feeds, collectors, and distributors. Methods to characterize the maldistribution must take into account the different nature of these flows. In the current analysis, the depth of penetration, l(m) of the maldistribution is defined and a method to estimate the depth, based on an approximate solution to the liquid and vapour transport equations within the packing is developed. Results using five flow distributions with both large scale and small scale maldistributions are presented, demonstrating the capability of the current method to characterize maldistribution.