Biomass estimation in cell suspension cultures of Capsicum frutescens and Daucus carota was correlated with the conductivity and osmolarity of the medium. The medium conductivity was influenced by nitrates, CaCl2, and minor and major elements. The addition of organic constituents such as vitamins did not substantially alter the conductivity. The addition of sucrose resulted in decreased conductivity of the culture medium. Changes in conductivity during the growth cycle were less sensitive to measurement regarding the small changes in biomass levels, because conductivity was contributed by electrolytes and not by the sugars that are the major components in the nutrient medium. In both C. frutescens and D. carota, the osmolarity sharply increased as a result of the rapid hydrolysis of sucrose into glucose and fructose, and then linearly decreased with the increase in biomass. Because all of the medium constituents contribute to the osmolarity value, its measurement correlated well with the increase in biomass in both cultures. Small changes in the biomass resulted in relatively wide osmolarity changes, thereby enhancing the sensitivity over conductivity measurement.