Neutron fluxes and reaction rates in MCNP output tallies are normalized per source neutron. Since the absolute normalization for the fixed source (NPS) calculations is straightforward, the absolute normalization for the criticality (KCODE) calculations is addressed. The correspondence between the MCNP calculated and measured flux is sought. The normalization constant at a certain thermal power of a neutron multiplication system is derived and discussed. This normalization constant is the same for both neutron flux and reaction rate tallies.