Technique for calculations of operating cusp emitter number at different stages of multicusp system shaping is proposed and tested experimentally. The shaping is carried out by means of thermal-field treatment and following thermal smoothing of emitter peaks. Experimental testing is realized using a π-shaped cathode with 11 cusps. Emission images are given of a multicusp field emitter after different shaping stages at the field-emission total current of 5·10^-7A. Nomograms are developed and presented in the paper for determination of the multicusp field cathode efficiency. Results of computer simulation coincide satisfactorily with experimental ones.