Abstract: This paper verifies an expression, which is rarelymentioned in textbooks, relating the results of 3-point and 4-pointbending tests of ceramic materials on fracture strength with theexperimental data obtained by Katayama. The expression is shown to be ofsatisfactory accuracy. The loadfactor for 4-point bending test, whose derivation is usually notincluded in textbooks, is also derived in this paper.