The JANKA test involves pushing a steel ball (0.444" in diameter) into a piece of lumber until half of the ball's diameter has penetrated.  The force necessary to do this is measured in pounds-force and becomes the comparison between hardness of different lumber species.

The higher the number, the harder the wood.  As a general statement tropical woods are harder than woods grown in temperate climates.

By JANKA Hardness Number		Alphabetical By Species
Wood Species	JANKA Number	Wood Species	JANKA Number
Brazilian Walnut Brazilian Teak Brazilian Rosewood Brazilian Cherry (Jatoba) Mesquite Caribbean Rosewood Santos Mahogany Asian Rosewood Merbau Jarrah Hickory Pecan Kempas Wenge Brazilian Maple North American Maple Bamboo Natural Australian Cypress White Oak Ash (White) Beech Angelique Teak Yellow Birch Red Oak Pine, Antique Heart Teak Bamboo Carbonized Walnut, American Black Cherry (Black) Honduran Mahogany Pine, Southern Yellow Douglass Fir	3680 3540 3000 2820 2345 2300 2200 2170 1925 1910 1820 1820 1710 1630 1500 1450 1410 1375 1360 1320 1300 1290 1260 1260 1225 1155 1120 1010 950 800 690 650	Angelique Teak Ash (White) Asian Rosewood Australian Cypress Bamboo Carbonized Bamboo Natural Beech Brazilian Cherry (Jatoba) Brazilian Maple Brazilian Rosewood Brazilian Teak Brazilian Walnut Caribbean Rosewood Cherry (Black) Douglass Fir Hickory Honduran Mahogany Jarrah Kempas Merbau Mesquite North American Maple Pecan Pine, Antique Heart Pine, Southern Yellow Red Oak Santos Mahogany Teak Walnut, American Black Wenge White Oak Yellow Birch	1290 1320 2170 1375 1120 1410 1300 2820 1500 3000 3540 3680 2300 950 650 1820 800 1910 1710 1925 2345 1450 1820 1225 690 1260 2200 1155 1010 1630 1360 1260