How to calculate Conversion Rates in Google Data Studio
In this post I’ll give you a quick example on how to calculate Conversion Rates in Google Data Studio.
Thanks to Lee Hurst (aka Helpful Lee) I know that the correct formula to calculate a conversion rate is;
SUM (converted leads) / SUM (total leads)
I had made the mistake of using the formula: converted leads / total leads which did not display the expected results.
Below is a Data Studio report for a fast food shop. Hypothetically this shop has been giving out free samples of its products, and want to keep track of how well their sales have been doing over time.
So they will use this formula to track the conversion rate:

Below is the Data Studio dashboard itself.
How to create a Conversion Rate dashboard
The first thing we should do is to add our sales and samples data to a Google Sheet.

I’ve also added an Image link for each food item, which will help us add images to our table.
The next step is to create a new Data Studio report and add the data to it as a source.

Before we create our table we need to create an Image field.
In this case we use the IMAGE function and link it to the existing Image Link field.

We now have our image field for the table.
We can now create our table.

Freshly created the table will look something like this.

The next step is to create our Conversion Rate field.
Click on ‘Add metric’.

Then click on ‘Create field’.

We can use the formula:
SUM(Items purchased)/SUM(Free Samples given)
And choose the number to display as Percent.

Our table should now look something like this:

We can pretty it up and bit and end up with a table that looks like this:

To cap things off we can also create a time series chart to show the Conversion rate compared to the free samples and sales over time.

We will need to recreate the Conversion rate for this chart, and make sure it is displaying on a right axis.
We should end up with a graph like this.

Hope this has been useful and helps you with any conversion rates you need to figure out!
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If you’d like to download one of my Google Data Studio reports as a template to use for your own data, you can visit Data Studio Templates and purchase one.