How to Use Parameters in Looker Studio

Building a great Looker Studio (formerly Data Studio) report often means turning a static page of charts into an interactive dashboard. You can make your reports much more powerful and user-friendly by adding parameters, which let viewers customize the data they're seeing without needing edit access. This guide will walk you through what parameters are and how to use them to create dynamic "what-if" scenarios, flexible filters, and interactive metric selectors.

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What Are Parameters in Looker Studio?

Think of parameters as variables that you or your report viewers can control. Unlike a fixed dimension (like 'Country') or metric (like 'Sessions'), a parameter holds a value that a user can change using a control like a slider, an input box, or a drop-down menu. When the user changes the parameter's value, any charts or calculated fields connected to it update instantly.

This opens up some fantastic possibilities for your reports:

• "What-If" Scenarios: Allow users to model potential outcomes. For example, "what would our projected revenue be if we offered a 15% discount?"
• Dynamic Segmentation: Let users define their own thresholds for segmenting data, such as "show me all products with a profit margin greater than X%."
• Interactive Filtering: Create custom filters that go beyond the basic dimension controls, allowing users to switch between complex, pre-defined segments.
• Metric Switching: Give users the ability to change the primary metric in a chart (e.g., switching a scorecard from showing 'Total Sales' to 'Average Order Value').

Essentially, parameters hand a degree of control over to the end-user, transforming them from passive viewers into active participants in the data analysis process.

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How to Create a Parameter in Looker Studio

Creating your first parameter is straightforward. Within your Looker Studio report, you'll find the option at the bottom of the data source property panel on the right side of the screen.

Here are the steps:

1. In your open Looker Studio report, make sure you have a data source connected.
2. In the Data panel on the right, click the blue "Add a Parameter" button at the bottom.
3. The parameter configuration screen will appear. This is where you'll define its properties.

Let's look at the configuration options:

• Parameter Name: A user-friendly name that will appear in your field list (e.g., "Discount Percentage Goal").
• Parameter ID: A unique ID with no spaces used to reference the parameter in calculated fields. Looker Studio will generate one from the name, but you can change it.
• Data Type: The type of value the parameter will hold. Your options are Text, Number (Whole or Decimal), and Boolean (True/False).
• Permitted Values: This controls how users can interact with the parameter.
• Default Value: The value the parameter will have when the report is first loaded.

Once you've configured your parameter, click Save. You will now see your new parameter in the data panel, identifiable by its distinctive purple [x] icon.

But creating a parameter is only half the battle. On its own, it does nothing. The real power comes when you connect it to your data using calculated fields and controls.

Example 1: Modeling a "What-If" Scenario for Sales Promotion

Let's build a simple report that helps a sales team project revenue based on a potential sales promotion discount. This is a classic "what-if" analysis perfect for parameters.

The Goal: Create an input box where a user can enter a discount percentage (e.g., 10%, 25%) and instantly see the projected revenue after that discount is applied.

Step 1: Create a Numerical Parameter

Start by creating the parameter that will capture the discount input.

• Click "Add a Parameter" in your data source.
• Parameter Name: Promotion Discount %
• Parameter ID: promotion_discount
• Data Type: Number (Decimal)
• Permitted Values: Range, from 0 to 1 (this will represent 0% to 100%).
• Default Value: 0

Now you have a parameter named promotion_discount ready to use.

Step 2: Create a Calculated Field Using the Parameter

Next, we need to create a new metric that calculates the discounted revenue. We'll add this as a calculated field within the data source.

• Click "Add a Field" in your data source.
• Name the field "Projected Revenue".
• The formula is where the magic happens. We'll multiply the total revenue by the remaining percentage after the discount:

SUM(Revenue) * (1 - promotion_discount)

• Make sure to set the new field's type to Currency. Click Save.

Step 3: Add a Control to the Report Canvas

Now, let's give the user a way to change the parameter's value directly on the report.

• In the main toolbar, go to Add a control > Input box.
• Place the input box on your report canvas.
• With the input box selected, look at the Setup panel on the right.
• Underneath the "Data source" setting, you'll see a field called "Control field."
• Click on the current dimension there, and from the field picker, select your Promotion Discount % parameter.

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Step 4: Visualize the Result

Finally, let's display our original revenue and our new "Projected Revenue" side-by-side so we can see the impact of our discount.

• Add two scorecards to your report.
• For the first scorecard, set the metric to your original Revenue.
• For the second scorecard, set the metric to our newly created Projected Revenue calculated field.

That's it! Now, a user can type a decimal value like 0.15 into the input box, and the "Projected Revenue" scorecard will instantly recalculate to show the revenue with a 15% discount applied. For a more intuitive control, you could use a slider instead of an input box.

Example 2: Creating a Dynamic Metric Selector with a CASE Statement

Another powerful application is allowing users to change the metric being displayed in a chart. Do they want to see Sessions, Pageviews, or Conversions in a time series chart? A parameter with a CASE statement can handle this easily.

The Goal: Create a drop-down menu that lets users switch the key metric in a scorecard and a time series chart.

Step 1: Create a Text Parameter for the Metric Choice

• Click "Add a Parameter".
• Parameter Name: Metric Selection
• Parameter ID: metric_selection
• Data Type: Text
• Permitted Values: List of values

Add the following values:

• Value: Sessions, Display As: Website Sessions
• Value: Total Users, Display As: Total Users
• Value: Conversions, Display As: Goal Conversions
• Default Value: Sessions

Step 2: Build the CASE Statement Calculated Field

Now, we create a single calculated field that will change its output based on the user's selection from the parameter.

• Click "Add a Field".
• Name the new field "Selected Metric".
• Use a CASE statement to check the value of the parameter and return the corresponding metric:

CASE
  WHEN metric_selection = "Sessions" THEN Sessions
  WHEN metric_selection = "Total Users" THEN Total Users
  WHEN metric_selection = "Conversions" THEN Goal Conversions
  ELSE 0
END

• Change the field data type to Numeric > Auto in the bottom-right of the calculation editor. Click Save.

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Step 3: Connect the Parameter Control and Charts

The final step is to put it all together on the canvas.

• Go to Add a control > Drop-down list and place it on your report.
• In its Setup panel, set the "Control field" to your Metric Selection parameter.
• Add a scorecard and a time-series chart to your report.
• For both the scorecard and the time-series chart, set the primary metric to your new "Selected Metric" calculated field.

Now your report viewers can use the drop-down menu to switch between "Website Sessions," "Total Users," and "Goal Conversions," and both charts will update instantly to show the chosen data.

Final Thoughts

Using parameters in Looker Studio transforms your static reports into powerful, interactive dashboards. By mastering what-if scenarios, dynamic filters, and metric selectors, you can provide far more value to your audience, enabling them to explore data and uncover insights on their own. They might seem a bit technical at first, but with a little practice, parameters will become an essential part of your reporting toolkit.

While the flexibility of tools like Looker Studio is great, building custom report interactivity for every question can become time-consuming. We built Graphed because we believe getting answers from your data shouldn't require you to become a dashboard engineer. Graphed connects to all your marketing and sales sources - like Google Analytics, Shopify, and Facebook Ads - and lets you create real-time dashboards and reports simply by asking for what you want in plain English. Instead of manually building parameters and CASE statements, you can just ask, "Show me a chart of my top 5 ad campaigns by revenue last month," and get an interactive visualization instantly, helping you and your team get back to making decisions instead of wrangling data.