How to Create Log and Semi-Log Graphs in Google Sheets

Log graphs have both axes scaled on log, and semi-log graphs have one of the two axes scaled on log. How to create them in Google Sheets.

Semi-log and log-log graphs are powerful tools for analyzing data. A relationship between two datasets might not show itself on a plain graph, while a log graph could bring its secrets to light.

Google Sheets is a capable spreadsheet app that allows you to create various types of charts. What's more, you can create semi-log or log-log graphs in Google Sheets with only a couple of clicks. Read on to learn how you can create logarithmic graphs in Google Sheets.

How to Create a Semi-Log Graph in Google Sheets

A semi-log graph is a graph that has a single logarithmic axis. In most cases, this is Y or the vertical axis. So in a semi-log graph, the Y-axis will be logarithmic, while the X-axis remains even.

To demonstrate this, let's take a look at an example. In this sample spreadsheet, we have the count of cells in cell culture on different days. Let's create a normal line graph, and then make the Y-axis logarithmic.

The first step, is to create a line graph in Google Sheets. Once you have a line graph, you'll need to go to the graph settings and make the vertical axis logarithmic.

1. Select your data table. That'll be A1 to B6 in this example.
2. Go to the Insert menu.
3. Select Chart.

Google Sheets will automatically determine the ideal chart type for this data table. Likely, your graph is already a line graph. However, if it's not, you can easily change it.

1. Double-click on your chart to bring up the Chart editor.
2. Go to the Setup tab.
3. Under Chart type, select Line chart.

Now you have your line chart. Take a look at the curve and remember what it looks like now for reference. It's time to turn this into a semi-log graph.

1. Double-click the graph to bring up Chart editor.
2. Go to the Customize tab and then Vertical axis.
3. Under Vertical axis, check Log scale.

Now you have a semi-log graph where the Y-axis is on a logarithmic scale. Take a look at your graph now. Since the values in our sample were exponential (they were all powers of 12), the logarithmic graph is a straight line.

Calculating the attributes and the course of a straight line is much easier, when compared to the previous graph.

How to Create a Log-Log Graph in Google Sheets

On some occasions, your analysis or calculation might require both axes to be on a logarithmic scale. That's where the log-log graph comes in. In a log-log graph, both the X and the Y axes are on a logarithmic scale. When both the Xs and the Ys are exponential, a log-log graph produces a straight line.

In a sample similar to the previous one, we have the cell counts of a culture in different days. This time the days, or the X axis, are exponential too. Just like before, you need to create a line graph first.

1. Select your data table. That will be cells A1 to B6 in this example.
2. Go to the Insert menu.
3. Click on Chart.

Google Sheets will automatically create a line graph for you. Now it's time to make that a log-log graph.

1. Double-click on the chart to bring up Chart editor.
2. Go to the Customize tab.
3. Open the Vertical axis tab and check Log scale.
4. Open the Horizontal axis tab and check Log scale.

Lo and behold! Your broken line is now a straight line when put on a log-log scale. Now you can discover the secret relations between your data with more ease.

Logarithmic Graphs in Google Sheets

Logarithmic scales on graphs are much like a key to a new world. Logarithmic scales grant you perspective and show you things that you couldn't see on an ordinary scale.

While a semi-log graph has a single axis on a logarithmic scale, a log-log graph has both axes on a logarithmic scale. Google Sheets can help you illustrate both of these graphs, and now you know exactly how to do that.

Source: MUO