Sometimes known as Compression Strength parallel to the grain, this is a measurement of the wood’s maximum crushing strength when weight is applied to the ends of the wood (compression is parallel to the grain).

Compression strength testing

Compression strength testing

This number is a good indicator of the wood’s strength in applications such as deck posts, chair legs, or other circumstances where the load being applied is parallel rather than perpendicular to the grain.

In practical terms, the number itself isn’t all that meaningful, but it becomes useful to use in comparison with other woods. For instance, Ipe is known to have excellent strength properties among imported species, and has a crushing strength of 13,510 lbf/in2 (93.1 MPa). In comparison, White Oak is a well-known wood used in cabinetry and furniture, and has a crushing strength of 7,440 lbf/in2 (51.3 MPa), and Redwood is commonly used for decking, and has a crushing strength of 5,690 lbf/in2 (39.2 MPa).