The period of economic transition in Poland at the beginning of the 1990’s was marked by great variations in prices and incomes. These variations were immediate causes of changes in the living standards of households. In this paper, we focus on the theoretical and empirical impact of these variations on the level of inequality and social welfare, as well as on the study of the link between this impact and the choice of utility functions. We distinguish two types of variations, that is, marginal and discrete variations in prices and incomes. Initially, we analyze the impact of marginal variations of prices and incomes on the level of inequality in the distribution of standards of living (calculated with the Gini coefficient). We then study the impact of non-marginal price and income changes on inequality as well as on social welfare. We illustrate these various approaches with Polish data.