An analytical method for the determination of nano particle sizes based on Debye theory using turbidity measurements has been developed. The method uses intercept at zero concentration to eliminate the affects of particle-particle interactions, and thus, improve the accuracy of the particle size measurement. Several factors that impact the reproducibility of measurements have been investigated. In this study, we have also compared the turbidity-Debye method to dynamic light scattering, field emission scanning electron microscope, and nitrogen sorption. Good results have been achieved using the turbidity-Debye method. The advantages and disadvantages of the method will be discussed.