This document specifies the test method to determine the extent to which ceramic powder compacts made of granulated or ungranulated ceramic powders are densified, when they are sintered at a high temperature without the application of any external pressure or external densification force. The test method is applicable to pure oxides, mixtures of oxides and solid solutions, and is also applicable to non-oxides (e.g. carbides, nitrides) that can be sintered under vacuum or constant gas pressure (1 bar or less) to prevent oxidation or decomposition. The test method is not applicable to ceramics that can only be sintered using pressure-assisted sintering techniques such as hot pressing (HP), hot isostatic pressing (HIP), gas pressure sintering (GPS) or spark plasma sintering (SPS). Inorganic sintering additives can be used where their presence is reported.