The size of the nanoparticles is important when it comes to changing the overall characteristics of a material. Thus, to explore the properties of the material, it becomes essential to study the size evolution of semiconducting nanoparticles. One technique that is frequently used to analyze the optical properties of particles with nanoscale size is UV-visible absorption spectroscopy. The average particle size in a nano colloid can also be determined using the absorption onset from UV-vis absorption in addition to optical characteristics . A lot of empirical or theoretical formulas are suggested by different researchers to estimate the size of nanoparticles with the help of calculated bandgap energy. In the present work, the following hyperbolic band model has been used to estimate the average particle size by taking into account the strong absorption edge in the sample's absorption spectra: