Objectives: To quantify the operational costs of a municipal public hospital in the city of São Paulo (Brazil) and to identify factors that led to cost increases during the year of 2016 using the absorption method. Methods: This was a retrospective study conducted between January and December of 2016 at Vila Santa Catarina Municipal Hospital, a public tertiary hospital in São Paulo, Brazil. Results: We identified and analyzed a total of 8702 inpatient data. Average day cost per patient was US$ 949, with a median of US$ 1,825, and a total operating cost of US$ 48,743,847. Transplant patients showed the highest median costs, while pregnant women had the lowest median costs, 69.9% of the 8,702 hospitalized patients was above the mean cost of US$ 3,068 registered for 2016. Age was associated with a 6.6% increase in cost for each one-year increase in age, while the cost associated with female patients was 1.1 times that of men. Patients who died in the hospital were 8 times more likely to cost more than patients who were discharged from the hospital. Oncology, transplant, and clinical-surgical patients had 18.8 times the cost of patients in the maternity unit, respectively. Conclusion: We identify the operating costs of the Vila Santa Catarina Municipal Hospital, where the average cost for the operation of the unit was US$ 133.179. The cost per patient was US$ 1,825.91. We also concluded as to the second objective that the cost increase factors were age and death.