Low consistency refining is primary means of improving the paper quality by imparting energy to fibres through repeated fibre-bar interactions. Useful part of the energy modifies the morphology of fibres and the remaining, no-load power, overcomes the hydraulic, pumping and mechanical losses in the refiner. In this study, effect of consistency, operational and plate design parameters on no-load power was experimentally determined on two pilot scale refiners with different diameters. Obtained data were used to provide a statistical model for prediction of no-load power. To study the effect of diameter and groove depth, no-load power of some mills were collected.