Blending Data Sources in Looker Studio: A Practical Guide

What Is Data Blending in Looker Studio?

Data blending in Looker Studio lets you combine data from two or more separate sources into a single chart or table. It is Looker Studio's equivalent of a SQL JOIN — you pick a common dimension (the join key), and Looker Studio merges the rows from both sources on that shared field.

The most common use case: combining Google Ads cost data with GA4 session behaviour data using campaign name as the join key, so you can see pre-click and post-click metrics in one table.

How to Create a Blended Data Source

1. Add two charts to your report — one from each data source you want to blend
2. Select both charts (Shift+click)
3. Right-click and select "Blend data"
4. Looker Studio opens the blend editor showing both data sources
5. Set the join key — the dimension that exists in both sources (e.g., Campaign Name)
6. Choose Left join (keeps all rows from the primary source) or Inner join (only rows matching in both)
7. Select which dimensions and metrics to include from each source

Common Blending Use Cases

• Google Ads + GA4: Join on Campaign → see Cost, CPA, ROAS alongside bounce rate and session duration
• Search Console + GA4: Join on Landing Page → see organic clicks and impressions alongside conversion rate
• Google Ads + BigQuery: Join on date or campaign ID → enrich Ads data with CRM revenue data

Blending Limitations to Know

Blending operates on aggregated data, not row-level data. This means you cannot blend two sources where you need row-level matching (e.g., matching individual users across platforms). For row-level joins, do the join in BigQuery first, then connect the output table to Looker Studio.

Blended sources also cannot use calculated fields that reference both original sources simultaneously — calculated fields belong to one source at a time.

When to Use BigQuery Instead

If your blend involves more than two sources, requires complex join conditions, or handles millions of rows, move the blending logic to BigQuery. Build the joined table there, then connect Looker Studio to the BigQuery output for fast, reliable rendering. Our Looker Studio service includes architecture recommendations for when BigQuery-backed reporting makes more sense than in-tool blending.