To calculate the area between two curves in DataGraph, you can use the same techniques for calculating the area under a curve. Specifically, the total integral is determined using the Expression variable and the cumulative integral is determined using the Plot Action column.

## Total Area

Here is an example dataset to illustrate.

Here is a plot of the two lines. The computed area between the two lines should be equal to 2.

Add an Expression variable as described in How to calculate the area under a curve. This time add the total integral of each column and give them different names (in this example ‘a’ and ‘b’). In the **Value** field, subtract the integrals to get the integral between.

Here is what the variable will look like. In this example, the value for Area equals 2.

## Cumulative Integral

To calculate a cumulative integral, start by calculating the difference between the two columns, using an Expression column.

Add a Plot action column and set y to the computed difference.