Block Strength

Hardness is a vanilla mechanic that determines how fast a block can be broken by the player, it is affected by Tool Speed and Haste on a private island and by on a public island.

For more information on how it works in the vanilla game and on private islands, see the official page on the Minecraft Wiki.

Formula
To determine the time to break a block we can use this formula (where $$miningTime$$ is measured in ticks.

$$miningTime = ceiling(600 * blockHardness / miningSpeed)$$

To get the time in seconds, divide the result by 20.

Softcap
Softcap limits how fast a block can be mined to at least 6 Minecraft ticks (or 0.3s). To determine the mining speed needed to hit the softcap of a given block, use the following formula:

$$softCap = blockHardness \times 100$$

The softcap can be bypassed by breaking a block instantly.

Instant Mining
To break a block instantly, you need to mine it in a single Minecraft tick (0.05s). To determine the mining speed needed to instantly break a block, use this formula:

$$instantMine = blockHardness \times 600$$

Mithril and Titanium cannot be instantly mined no matter how high your is.