This reply addresses some fundamental questions related to estimated sintering pressures. The additional contribution of grain boundary energy to sintering pressure varies depending on the calculation method and assumption, unlike the comment by Wakai. For the grains adjacent to a pore with non-equilibrium shapes, the pressures at the pore surface and grain boundary need to be clarified to estimate the sintering pressure properly. Application of the energy variation method to the local geometry also suggests a need for further consideration. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.