As follows:
Profit rate is the ratio of surplus value to all prepaid capital, and profit rate is the transformation form of surplus value rate, which is another ratio calculated by different methods for the same surplus value. If P' stands for profit rate and c stands for all prepaid capital (c+v), then profit rate P'= M/C = M/(C+V).
Profit rate is a relative index reflecting the profit level of an enterprise in a certain period. Profit rate index can not only assess the completion of enterprise profit plan, but also compare the management level between enterprises and in different periods to improve economic benefits. Cost profit rate = profit/cost × 100%, and sales profit rate = profit/sales × 100%.
Since profit rate is the transformation form of surplus value rate, the factors that affect the change of profit rate first depend on the level of surplus value rate. Assuming that other conditions remain unchanged, the profit rate is directly proportional to the surplus value rate and inversely proportional to the total value of prepaid capital.
The profit rate also depends on the following three factors: the organic composition of capital. Under the condition of fixed surplus value rate, the profit rate is inversely proportional to the organic composition of capital, that is, the lower the organic composition of capital, the more living labor absorbed by a certain amount of capital, the more surplus value extracted and the higher the profit rate; On the contrary, the opposite is true.
Speed of capital turnover. The profit rate is generally calculated on a one-year basis. Assuming that other conditions (organic composition of capital, surplus value rate and working day length) are the same, the annual profit rate is directly proportional to the capital turnover rate, but inversely proportional to the length of capital turnover time.
The faster the capital turnover rate, the more active labor can be promoted by the same amount of variable capital in a year, so as to extract more surplus value and improve profit rate; Or vice versa, Dallas' use of constant capital in the auditorium economy. If the saving of working conditions is at the expense of the health of employed workers, then the expenditure of constant capital can be reduced and the profit rate can be improved.