Properties of liquids on border of the unit can differ essentially from properties inside it. Definition of properties of a liquid on borders of the unit is necessary for a different sort of physical, chemical and biological researches. For applied and scientific researches the direct estimation of factor of a superficial tension from known potential of interaction between molecules of a liquid, for example, potential Lennard-Johnes is desirable. In article the theoretical estimation of factor of a superficial tension of water on known molecular potential of interaction Lennard-Johnes is resulted.