The economic efficiency of the enterprise and the length of its operation, the full utilization of mineral reserves and the total cost of operation depend on the selected depth and boundaries of opencast mining. In such conditions of the deposits` development it is necessary to evaluate the capabilities of the raw material base for the further development of the mining enterprise. The basis for determining of the border overburden ratio is on the condition that the price of manufactured marketable output of the designed enterprise should not exceed the price of the same marketable output in the world market. The realization of this condition is achieved analytically. This takes into account the impact of the rate of return on the final depth of the designed open pit. A new method of determining of the border overburden ratio is developed, which ensures the competitiveness of iron ore concentrate in the world market. The value of the border overburden ratio is developed for the Pershotravnevij open pit of the Northern MPP, depending on the situation of the iron-containing products` prices, which ensures the competitiveness of marketable iron-ore output in the domestic and world markets.