The Janka hardness scale is a great tool to use when considering your choice of hardwood flooring species. It is perhaps the most important test, as it measures the hardness of the wood species. More specifically, the Janka hardness test for hardwood flooring measures the force required to embed a .444 inch steel ball to half its diameter in the hardwood.

The hardness is expressed numerically as the pounds per square inch of pressure required to sink the ball into the species of hardwood where the higher the number, the harder the hardwood. The Janka hardness test is done on both the side and on the end of the hardwood due to the fact that hardness varies with the grain.

The Janka hardness scale is the industry standard for judging the ability of various hardwood flooring species to withstand denting and wear. It also indicates the effort required to either nail or saw the particular wood and therefore, also helps determine whether the hardwood is suitable for flooring.

This is also something to keep in mind when you are deciding whether or not to do the installation on your own or if you will be hiring a professional installer.

So what species can you reference for hardness? Red Oak hardwood flooring, which has a Janka rating of 1290, is the flooring industry benchmark for comparing the relative hardness of different wood species.

Following are some of the most popular hardwood species used in flooring along with their respective hardness ratings according to the Janka hardness test:
American Black Cherry (950)
American Black Walnut (1010)
Yellow Birch (1260)
Red Oak (1290)
White Ash (1320)
White Oak (1360)
Hard Maple (1450)
Santos Mahogany (2200)
Brazilian Cherry (2345)
Ebony (3220)
Brazilian Teak (3540)
Brazilian Walnut (3680)

The Janka hardness scale was originally produced as a variation on the Brinell hardness test. In Janka’s original test the results were expressed in units of pressure, but when the ASTM standardized the test (tentative issue in 1922 with the standard first formally adopted in 1927), it called for results in units of force. The results are stated in various ways in different countries, which can lead to confusion, especially since the name of the actual unit employed is often not attached.

In the United States, the measurement is in pounds-force. In Sweden it is apparently in kilogram-force (kgf), and in Australia, Janka hardness ratings are either in newtons (N) or kilonewtons (kN). Sometimes the results are even treated as units (for example - 360 janka).