Total number and angular albedo were calculated for commonly used shielding materials, water, concrete, and iron, for photons with initial energies from 10 keV up to 10 MeV and normal incident angle. Influence of material thickness on total number albedo was also investigated. Double differential albedo was determined from simulation of photon transport through materials by using PENELOPE and MCNP software. Backscattered photons were scored and grouped in equal intervals of energy and angle. Analytical expressions for angular and total number albedo as a function of initial energy were obtained. It was shown that angular albedo can be determined with the same formula for three examined materials. Corresponding analytical expressions for number albedo as a function of material thickness were presented in this paper. [Projekat Ministarstva nauke Republike Srbije, br. 171021]