Two different types of approach are available for calculating sintering kinetics: local and global. The local approach is based on the capillary pressure of the pore itself, while the global approach is based on the sintering pressure of the compact, which can be deduced under the assumption of a quasi-equilibrium state of the system. This paper identifies the fundamental difference between the two approaches and the sintering pressure to be the capillary pressure of the pore. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.