A method for tuning a filter component using size adjustment includes measuring a first frequency of a first resonant mode of a dielectric resonator component of an RF filter, said dielectric resonator component being a block of dielectric material having a cuboid shape with three pairs of opposite faces. The first resonant mode has an electric-field component oriented in a direction perpendicular to one of the pairs of opposite faces and parallel to the other two pairs of opposite faces. When a measured value of the first frequency of the first resonant mode is less than a desired value, dielectric material is removed uniformly from at least one face of the two pairs of opposite faces parallel to the electric-field component of the first resonant mode to maintain the cuboid shape of the block of dielectric material. The removal of the dielectric material may be by at least one of lapping, grinding, and milling. The first frequency of the first resonant mode is remeasured to check whether a remeasured value therefor is closer or equal to the desired value without exceeding the desired value. The method is also applicable for tuning multiple modes of dielectric resonator component in the form of a block of dielectric material having a cuboid shape, as well as for tuning multiple modes in dielectric resonator components in the form of blocks of dielectric material having cylindrical and spherical shapes.