The Janka Hardness Test for Wood / Bamboo

On most Hardwood / Bamboo flooring products, you will see a Janka Hardness Rating.  How are these ratings derived?

The Janka hardness test measures the hardness of wood bymeasuring the force required to embed a ~0.5" steel ball into wood to half its diameter.  It is one of the best measures of the ability of a wood species to withstand denting and wear. It is also a good indicator of how hard a species is to saw or nail.

The hardness of wood usually varies with the direction of the wood grain. If testing is done on the surface of a plank, perpendicular to the grain, the test is said to be of "side hardness." Testing the cut surface of a stump would be called a test of "end hardness."

A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring.

The Janka Hardness test below is done in accordance with ASTM D 1037-7 testing methods.  Note these numbers are an average! A standard deviation exists for each species, but these numbers do not get published. The chart is not an absolute; it is meant to help you understand which woods are harder than others. There are other factors that can affect how flooring performs: type of core (for engineered flooring), grain direction and thickness floor or top wear surface.