We investigate the size-dependent optical absorption coefficients of CdSe nanocrystals at both the band-edge and high within the absorption profile. The absorption properties in both of these regions must be selfconsistent to ensure accuracy of the measured coefficients. By combining transmission electron microscopy and inductively coupled plasma-optical emission spectroscopy, we map out the optical absorption properties and establish reliable size-dependent band-edge calibration curves. The measured absorption properties are compared to a simple 0D confinement model, to classical theory based on light absorption by small particles in a dielectric medium and to state-of-the-art atomistic semiempirical pseudopotential modeling. The applicability of these newly established calibration curves is demonstrated by analyzing the nucleation and growth kinetics of CdSe nanocrystals in solution.