21% to 31%. In the catering industry, the highest proportion of rent to turnover should not exceed 31%, and 21% to 31% quality inspection room is the most suitable. Too high will affect the restaurant's net profit. Catering industry is a food production and operation industry that provides consumers with all kinds of drinks, food, consumption places and facilities through instant processing, commercial sales and service labor. According to the definition of Standard Industrial Classification in Europe and America, the catering industry is a catering service organization.