This International Standard specifies a test method for determining the fracture toughness of monolithic ceramic materials at room temperature by the chevron-notched beam (CNB) method. This International Standard is applicable to monolithic ceramics and whisker- or particulate-reinforced ceramics that are regarded as macroscopically homogeneous. It is not applicable to continuous-fibre reinforced ceramic composites. This International Standard is usually applicable to ceramic materials with a fracture toughness less tan about 12 MPa(m1/2). The test method is applicable to materials with a flat crack-growth resistance curve and may be applicable to materials with a rising crack-growth resistance curve (R-curve).