Enter the pH, Temperature Factor, Calcium Hardness Factor, and Alkalinity Factor into the calculator to determine the Calcium Saturation Index.

## Calcium Saturation Index Formula

The following formula is used to calculate the Calcium Saturation Index (CSI).

CSI = pH + TF + CF + AF - 12.1

Variables:

- CSI is the Calcium Saturation Index
- pH is the measure of acidity or alkalinity of the water
- TF is the Temperature Factor
- CF is the Calcium Hardness Factor
- AF is the Alkalinity Factor

To calculate the Calcium Saturation Index, add the pH, Temperature Factor, Calcium Hardness Factor, and Alkalinity Factor together. Then subtract 12.1 from the total.

## What is a Calcium Saturation Index?

The Calcium Saturation Index (CSI) is a measure used in water chemistry to determine the potential for calcium carbonate to precipitate or dissolve in water. It is calculated based on the water’s pH, temperature, calcium concentration, alkalinity, and total dissolved solids. A positive CSI indicates that the water is oversaturated with calcium carbonate and may cause scaling, while a negative CSI means the water is undersaturated and may lead to corrosion.

## How to Calculate Calcium Saturation Index?

The following steps outline how to calculate the Calcium Saturation Index (CSI).

- First, determine the pH value of the water.
- Next, determine the Temperature Factor (TF).
- Next, determine the Calcium Hardness Factor (CF).
- Next, determine the Alkalinity Factor (AF).
- Finally, calculate the Calcium Saturation Index (CSI) using the formula: CSI = pH + TF + CF + AF – 12.1.

**Example Problem:**

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

pH = 7.5

TF = 0.2

CF = 0.8

AF = 1.5