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.

So. Yellow Pine 690
American Cherry 950
Teak 1000
Black Walnut 1010
Carbonized/ Carmel Bamboo 1120
Heart Pine 1225
Yellow Birch 1260
Red Oak (Northern) 1290
American Beech 1300
Ash 1320
White Oak 1360
Australian Cypress 1372
Natural Bamboo 1410
Hard Maple 1450
Brazilian Oak 1460
Brazilian Maple 1500
Angelim 1720
Hickory/ Pecan 1820
Purpleheart 1860
Moabi 2050
South American Pearwood 2100
Tigerwood 2160
Santos Mahogany 2200
Tatajuba 2220
Jatoba (Brazilian Cherry) 2760
Tiete Rosewood 3200
Cumaru (Brazilian Chestnut) 3540
Ipe (Brazilian Walnut) 3680