The budget is a tool of extreme importance in construction. It is from this that a cost forecast is obtained. In this way, this work had as objective to compare analytical budget with real cost obtained in the construction of a public nursery school held Construtora Monteiro & Pereira Ltda. For its development, it was used as methodology the analysis of budgetary worksheets and descriptive memorials that referred to the budgeting of the construction of a public nursery school. The results showed that the budget developed by the developer clearly showed the services and their respective costs, where they were detailed in a clear and precise way. At the end it was concluded that although the result was satisfactory, it was verified that there was an increase in the real cost of the work because the fixed costs incur changes in values, as the employees were admitted and / or fired.