How to Find Slope of Logarithmic Graph in Excel (with Easy Steps)

By adjusting a few axis format variables in Excel, we can simply plot a log-log graph. Both axes in the log-log or natural log-log graph are really on a logarithmic scale. Similar to the equation y = c. x^a, this graph illustrates whether the variables are in a constant power relationship. In this case, the X and Y are related by a power of ‘a’ as in the image below.

The line should have a smaller curve if a dataset derived from this equation is shown using a logarithmic scale.

Step 1 – Create a Logarithmic Graph by Using the Charts Tool of Excel

Select the Scatter Chart from the Charts group under the Insert tab.

A blank chart will appear.
Right-click on the chart and choose the command Select data from the context menu.

A new window titled Select Data Source will appear. Click the Add command icon in that window.

Choose the range of cells that we will use as data for the X-axis and the Y-axis in the following window.
Choose the cell address that currently has the cells and cell name in it to insert the title there.

Click OK.

Right-click on the labels for the Horizontal Axis to generate the logarithmic graph.
Select Format Axis from the context menu.

It will reveal a new side panel. Select the Logarithmic scale checkbox and enter Base 2.7 under the Axis Options in the Format Axis side panel.
Set Vertical Axis Crosses to Automatic as well.

Similar to the y-axis, check the Logarithmic scale checkbox for the x-axis under the Axis Options in the Format Axis side panel.

Step 2 – Find the Slope of the Logarithmic Graph

We have data that could fit the theoretical y = c. x^a curve. The slope of a natural log-log plot is equal to the exponent a‘s value, which is calculated as

a=ln(y2)-ln(y1)/ln(x2)-ln(x1)