The average effect and average excess both measure the phenotypic effects of gametes in a population. A matrix notation is introduced that provides a general analytical solution for the average effects at a single locus with k alleles that can be solved for any population regardless of its genotype frequencies. This same notation also provides an easy way of deriving and generalizing to k alleles the well-known relationships between average effects and average excesses that exist under random-mating and regular deviations from Hardy–Weinberg equilibrium due to inbreeding.