<p>Understanding the optical parameters of skin tissues are required to diagnose the abnormalities of the skin and for therapeutic purposes. Different researchers have done Monte Carlo-based simulations, in vitro and in vivo experiment in discrete or in short wavelength range to assess several optical parameters, but an in vivo assessment in UV–Vis-NIR range for most of the parameters associated to skin tissue optics has rarely been explored. Human skin forearm reflectance spectra has been taken from the online data repository, and the main optical parameters related to skin, like absorbance coefficient (µ_a), scattering coefficient (µ_s), reduced scattering coefficient (µ_s^ʹ), and other derived optical parameters such as diffusion and attenuation coefficient, anisotropy factor etc. has been assessed analytically in the wavelength range of 250–2500&#xa0;nm. Variation of the parameters at different wavelength regions has been observed and compared by using different equations. Further, by taking calculated parameters, simulation has been done in COMSOL Multiphysics to access 3D and 2D fluence distribution in 601–1261&#xa0;nm wavelength ranges, with 60&#xa0;nm interval. It has been observed that 3D fluence distribution within skin varies with wavelength dependent absorption and scattering, hence the chromophores and scattering components distribution within different layers and, two dimensional fluence distribution varies along different surfaces/layers according to source position and source to detector distance.</p> Graphical abstract <p></p>