Current game stage: 1
The Hardness index of a material determines how much effort is needed to break the material. You can obtain this index using the Item Stats functionality added to the game in the alpha 7.6. To do this, place the mouse over an item to see the Object Stats, including its Hardness.
x = Hardness ÷ Block Damage (Appropriate Tool)
If x = Integer
Then Durability = x + 1
Else Durability = RoundUp(x)
In words: Divide Hardness by the Block Damage of the Appropriate Tool and add one if whole number or round up the quotient.
x = Hardness ÷ 0.075 (Entity Damage Infected Survivor)
Pure-Dur = RoundUp(x)
In words: Divide Hardness by 0.075 and round up the quotient.