How do you determine the precise painting service cost for a Living Room in Lugano, considering excluding ceilings, 2 doors, and 2 windows, with dimensions of 3m x 8m?

Determining the precise painting service cost for a Living Room in Lugano, considering excluding ceilings, 2 doors, and 2 windows, with dimensions of 3m x 8m, it turns around a cost of CHF 255.00.

*) The calculations are approximate, based on a room height of 2.4m, and include one coat of paint. The price covers only the labor, excluding any services or materials.