The aim of this chapter is to examine what types of computations Mesopotamian scribes were trained when dealing with building activities. Its aim is also to try to determine how far these calculation methods were actually used in practice. In order to do this we examine mathematical and administrative texts dealing with construction activities as well as archaeological and ethnographical data. Two types of texts provide the information on mathematical calculations for construction on which we draw: mathematical texts and practical administrative texts. We distinguish between three different steps in these computations. The first is the use of labor norms. In this category we find the daily tasks (called iškarum) expected from unskilled workers. The second step is the use of coefficients to calculate a magnitude on the basis of other magnitudes (determining a volume from a given weight, for instance). The last step consists of exercises dealing with several types of tasks, using combined coefficients. Finally, by drawing on some administrative construction texts, we try to check whether or not these computations were actually used in practice.