Cross-Platform
advanced
5 min read5 steps181 views

Looker Studio Calculated Fields and Custom Metrics for Ads

Looker Studio calculated fields let you create custom metrics not available in standard data sources. Common examples: ROAS (Revenue/Cost), CPA (Cost/Conversions), CTR (Clicks/Impressions×100), lead-to-sale rate, profit (Revenue - Cost), and blended CPA across platforms. Create calculated fields in

Reporting & Dashboardslooker studio calculated fields custom metrics

Quick Summary

Looker Studio calculated fields let you create custom metrics not available in standard data sources. Common examples: ROAS (Revenue/Cost), CPA (Cost/Conversions), CTR (Clicks/Impressions×100), lead-to-sale rate, profit (Revenue - Cost), and blended CPA across platforms. Create calculated fields in the data source editor or at the chart level. Use CASE statements for conditional logic (e.g., campaign type labels) and mathematical operators for custom formulas.

Process Flow

Interactive diagram — drag to pan, scroll to zoom

Step-by-Step Guide

Follow these 5 steps to complete this guide

1

Creating Calculated Fields

In Looker Studio, go to your data source > Add a field > write your formula. Or click 'Add a field' within a chart for chart-specific calculations.
2

Common Formulas

ROAS: `Revenue / Cost` CPA: `Cost / Conversions` Profit: `Revenue - Cost` Conversion Rate: `Conversions / Clicks * 100`
3

CASE Statements

Use CASE for conditional logic: `CASE WHEN Campaign_Name CONTAINS 'Brand' THEN 'Brand' WHEN Campaign_Name CONTAINS 'Search' THEN 'Non-Brand' ELSE 'Other' END`
4

Blended Metrics

To calculate metrics across platforms (blended CPA, total spend), use data blending. Add multiple data sources and blend on a common dimension (date). Create calculated fields on the blended data.
5

Best Practices

Name calculated fields clearly. Document formulas. Test with known values to verify accuracy. Use calculated fields for metrics that your team actually needs — do not create everything possible, just what drives decisions.

Was this guide helpful?

Your feedback helps us improve our guides