The work is devoted to the search for methods for calculating the heat consumption of multi-apartment residential buildings for heating and hot water supply, which allows obtaining the closest results to the actual ones. Three current methods of calculating heat consumption and one canceled, but often used in heat supply contracts, were used. Based on a comparison of the actual data obtained by the common-house heat energy metering devices and the calculated values, the possible deviations in the heat consumption of multi-apartment residential buildings of different floors, area and year of construction, ranging from 49.73 to 177.77%, were found. An economic assessment of the consequences of using the most inadequate methods has been carried out. It was found that when using methods with extreme error values, payments for the heat supply service from one house can differ by 3.6 times.