Enter the plastic limit, the natural water content, and the plasticity index into the Liquidity Index Calculator. The calculator will evaluate the Liquidity Index.

## Liquidity Index Formula

The following formula is used to calculate the Liquidity Index.

LI = (PL - NWC) / PI

Variables:

- LI is the Liquidity Index ( )
- PL is the plastic limit
- NWC is the natural water content
- PI is the plasticity index

To calculate the liquidity index, subtract the natural water content from the plastic limit, then divide by the plasticity index.

## How to Calculate Liquidity Index?

The following steps outline how to calculate the Liquidity Index.

- First, determine the plastic limit.
- Next, determine the natural water content.
- Next, determine the plasticity index.
- Next, gather the formula from above = LI = (PL – NWC) / PI.
- Finally, calculate the Liquidity Index.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem:**

Use the following variables as an example problem to test your knowledge.

plastic limit = 50

natural water content = 40

plasticity index = 2.5LI = (PL – NWC) / PI =** ** ?