The origin of light neutrino masses remains an unknown, though at present the most widely accepted model for understanding the smallness of the masses observed in nature is the Seesaw Mechanism. The Littlest Seesaw model extends the SM by two right-handed neutrinos with constrained Yukawa couplings and provides a highly predictive description of neutrino masses and PMNS mixing parameters. If realised at high energies there will be renormalisation group corrections to the low energy predictions, which depend on the right-handed neutrino masses. In this project, we perform a chi-squared analysis; using a four-parameter fit to the low energy neutrino parameters, combined with input from leptogenesis, we aim to accurately predict for the first time the masses of these two heavy neutrinos.