A method is provided to control the feed of a metal charge into an electric arc furnace having at least one electrode to generate an electric arc to melt metals. The method includes: a step of defining a “cover index CI” of the electric arc by the slag present above the liquid metal bath, in order to calculate which of the harmonics present in an electric feed quantity of the furnace are taken into consideration; a step of measuring the actual cover index CI value during a functioning cycle of the furnace; and a step of adjusting the speed of feed of the metal charge into the furnace based on the measured value of the cover index CI.