A method is proposed for eliminating the error of vertical gravity gradient from absolute measurements of gravity. The method involves precise determination of effective measurement heights for each individual measurement and referring the measured gravity to the arithmetic average of those heights. It is shown that the average effective measurement height for a set of measurements preserves the property of the regular effective measurement height for a single measurement, namely the average gravity value referred to the average effective measurement height does not depend on the gradient value, Precise determination of individual effective measurement heights with absolute gravimeter's weighting functions is discussed.