The room temperature experimental Mn K-edge X-ray absorption spectra of La$_{1-x}$Sr$_{x}$MnO₃ ($x = 0-0.7$) are compared with the band structure calculations using spin polarized density functional theory. It is explicitly shown that the observed shift in the energy of Mn K-edge on substitution of divalent Sr on trivalent La sites corresponds to the shift in the center of gravity of the unoccupied Mn $4p$-band contributing to the Mn K-absorption edge region. This correspondence is then used to separate the doping and size contributions to the edge shift due to variation in the number of electrons in valence band and Mn-O bond lengths, respectively, when Sr is doped into LaMnO₃. Such separation is helpful to find the localization behaviour of charge carriers and to understand the observed transport properties of these compounds.