| Species | Hardness, lbf | Bar | vs. red oak | Density, lb/ft³ |
|---|
No species match.
This list:
The force needed to press a steel ball 0.444 in (11.28 mm) across halfway into the side of a board, averaged over the radial and tangential faces. The figures are side hardness at 12% moisture content, the usual basis for dry wood; a few imports were tested at 15%. Wetter wood is softer.
Comparing how well woods resist dents and wear: floors, tabletops, workbench tops, stair treads, tool handles and cutting boards. Harder woods also dull tools faster and are more likely to need pilot holes for nails and screws. Hardness varies between boards of a species by about 20%, so close figures are a tie.
No standard design formula takes Janka hardness as an input. Strength, stiffness and fastener values come from other tests and from density; the calculators on this site use stiffness, shrinkage and density instead. Hardness is a comparison: the ratio column shows how a wood ranks against one you know. The flooring trade compares with northern red oak, at 1,290 lbf.
Denser woods are harder, and hardness rises faster than density: among hardwoods, doubling the density roughly quadruples the hardness. The handbook fits side hardness at 12% moisture content to specific gravity G as 3,440 × G2.09 lbf for hardwoods and 1,930 × G1.49 lbf for softwoods.
Estimated: 13 domestic species without a measured value are estimated from their density with those fits. Individual species can stray well off the fit; osage orange, measured at 2,620 lbf, would be estimated at about 1,950.
Names follow the USDA Wood Handbook, with trade names in the search: typing jatoba finds courbaril, and hard maple finds sugar maple. Imported species sold under one trade name can come from several botanical species, so their hardness varies more.