The work herein concerns a seed grader. The authors of the article deal with graders powered with two vibrators working in the concurrent self-synchronization system. The objective of the paper was to determine the efficiency of passing seeds though subsequent sieves in the sieve column of the seed calibrator. Seeds divided into fractions were sieved through subsequent three sieves counting to the top of a sieve, whose mesh diameter was smaller than the biggest dimension of a seed. Efficiency of passing seeds through a sieve of diameter Dk=0.565 m was researched. Efficiency of passing seeds of different fractions through subsequent sieves is similar. The lowest intensity of seeds occurs in the moment of passing seeds through a sieve with the openings diameter equal to the upper border of a dimension of a given fraction. The obtained results allow selection of appropriate intensity of dosing seeds to a vibrating calibrator.