European standard NBN EN 12372

The flexural strength - sometimes also referred to as the bending tensile strength or tensile strength - is expressed in Newtons per square millimetre and indicates the maximum pressure that a stone can bear for this specific type of load.
The flexural strength is always much lower than the compressive strength (approximately 1/10 for granite/marble and 1/15 for sandstone). The bending capacity can be very important for certain natural stone applications, such as freestanding staircases or overhangs. It is also important to take account of bending capacity when there is a high risk of cracks forming, as a result of shrinkage and/or thermal stresses.