The paper shows the ways to estimate the biological freshness of eggs. Was undertaken a comparative study of the existing methods for estimating the “age” of the eggs, such as the size of the air hood, the weight, Xay units or indexes of albumin and vitelline, the dynamics of aging and the impact on the rate of aging of certain biophysical indicators of the eggs, such as the weight, the shell thickness, the elastic deformation, etc. The density indicator of the chicken and quail eggs is studied, as the most reliable characteristic for the determination of their “age”, its advantages and disadvantages. The concepts of “hydradensity”, “freshness index” of the eggs were introduced. Were shown the time periods the eggs take to come to the surface, depending on the average daily hydradensity and moisture loss. The dynamics of the freshness index of the eggs, which were kept in accordance with All Union State standard at 11-13º and 85% of relative humidity, were given.