Janka is a test that measure the hardness of a wood. The test measures the force required to push a steel ball with a diameter of 11.28 millimeters (0.444 inches) into the wood to a depth of half the ball's diameter, thereby giving an idea of it's hardness and durability. The higher the number, the harder the wood. The type of wood that is included in the scale are:

Brazilian Walnut, IPE, Bolvian cherry, Brazilian Teak, Cumaru, Tiete Rosewood, Madeira Nova, Angelim, Angelim Pedra, Brazilian Rosewood, Tamarindo, Angico, Vermelho, Patagonian Rosewood, Brazilian Cherry, Jatoba, Mesquite, Santos Mahogany, Tiggerwood, Mauracatiara, Merbau, Amendoim, Ybyraro, Purple Heart, Hickory, Pecan, Bolivian Rosewood, African Perdauk, Patens, Timbergrass Bamboo, Wenge, Junkers Beech, Hard Maple, Australian Cypress, White Oak, Vint. Oak, White Ash, American Beech, Northern Red Oak, Yellow Birch, Heart Pine, Black Walnut, Teak, Cherry, American/Black, Southern Yellow Pine, Yellow Pine, Douglas Fir.