This article presents two models of Polish peasant budgets. The first is a theoretical budget of a medieval peasant family and the second is a similar model for the early modern period, confirming some of the characteristic features of the transitional period in the Polish economy in this period. Variables taken into account in the construction of the budgets include the average size of a peasant farm, its productivity, the distribution of crops, family size, rents and taxes paid to the state, Church and feudal lords. The two factors that appear to have had the greatest impact on peasant budgets during the fifteenth and sixteenth centuries were the decrease in farm size and the sharp rise in grain prices in the sixteenth century. As a result, although comparison of the two models indicates a decrease in the level of commercialization of the average Polish peasant farm, the financial resources of Polish peasants actually grew.