Janka hardness test

[citation needed] It measures the force required to embed an 11.28-millimeter-diameter (7⁄16 in) steel ball halfway into a sample of wood.

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

When testing wood in lumber form, the Janka test is always carried out on wood from the tree trunk (known as the heartwood), and the standard sample (according to ASTM D143) is at 12% moisture content and clear of knots.

The results are stated in various ways, leading to confusion, especially when the actual units employed are often not attached.

The chart is not to be considered an absolute; it is meant to help people understand which woods are harder than others.