Workload capacity, an important concept in many areas of psychology, describes processing efficiency across changes in workload. The capacity coefficient is a function across time that provides a useful measure of this construct. Until now most analyses of the capacity coefficient have focused on the magnitude of this function, and often only in terms of a qualitative comparison (greater than or less than one). This work explains how a functional extension of principal components analysis can capture the time extended information of this functional data using a small number of scalar values chosen to emphasize the variance between participants and conditions. This approach provides many possibilities for a more fine grained study of differences in workload capacity across tasks and individuals.