Seed grading is an important practice for better crop and also useful in separation of quality seeds in a seed lot. The aim of grading is to improve the uniformity of the seed lot by removing seeds of the same species with low quality. The present study was carried out to find out the optimum sieve size for size grading of seeds of barnyard millet (Echinochloa frumentacea L.) MDU1. The effect of seed size on physiological parameters were evaluated using BSS 10×10, BSS12×12 and BSS14×14 wire mesh sieves along with control. The barnyard millet seeds graded with BSS12×12 recorded higher seed recovery (76.67%) than other sieves used with required germination (92%), 1000 seed weight (3.9g), root length (14.1cm), shoot length (8.45cm), dry matter production (0.027g/10 seedlings) and vigour index (1983). Hence, seeds of barnyard millet MDU1 could be size graded using BSS12×12 sieve for more seed recovery with required seed quality standards as compared to BSS 10×10, BSS14×14 and ungraded seeds.