How to connect Looker Studio to GA4 without the rookie mistakes

In Looker Studio, click Create → Data source. In the connector gallery, search "Google Analytics."

Click the Google-authored connector (blue G icon, says 'By Google'). Authorize access if prompted.

On the account picker screen, you'll see two tabs at the top: "GA4" and "Universal Analytics." UA is end-of-life since July 2024 — pick GA4 unless you have an archived UA property you specifically need.

Drill: GA4 Account → Property → Data Stream. Pick the production web stream (usually named after your domain). If you have multiple streams for staging vs. production, pick production carefully.

Click Connect (top-right). You'll see the GA4 field schema — every dimension and metric, around 200+ fields.

Look at the field list. Each row has Name, Type, Aggregation, and Description columns.

Find any dimension you'll use frequently with a confusing name. For example, "Session source / medium" is the standard channel field — rename it to "Channel" if your team uses that vocabulary.

Find any metric defaulting to SUM that should be AVERAGE (Engagement rate, Bounce rate, Conversion rate). Click the aggregation cell and switch.

Hide fields you'll never use to reduce the schema noise — click the eye icon on rows like "Audience name" or technical fields.

Add calculated fields here once (not per-report) — e.g., a custom 'Cost per session' that requires blending Google Ads cost data isn't done here, but a simple ratio of Conversions / Sessions can be (see tutorial 6).

After saving the field config, click Edit Connection (or back into the data source from Home). Find the Credentials section.

For most marketing dashboards, set to Owner's credentials. This means everyone who views your report sees data through your access — you don't need to grant every viewer GA4 access.

For internal BI where access control matters at the row level, use Viewer's credentials. Each viewer needs GA4 viewer access on the property.

Refresh frequency: GA4 sources default to 12 hours. Lower to 1 hour only if you actually need it — faster refresh consumes more API quota and rarely changes the decisions made from the dashboard.

Save the data source. Name it clearly: "GA4 — Acme.com (Production)". Future-you will appreciate the explicit naming when there are five sources to pick from.

From the data source, click Create Report (top-right). Looker Studio creates a new report with your GA4 source pre-attached.

Add a Date range control (Insert → Date range). Set default to Last 28 days.

Add a Scorecard with Metric = Total users. The number should appear within 5 seconds.

Add a Table with Dimension = Session source / medium, Metric = Sessions. The top row should be a recognizable channel (google / organic, direct / none, google / cpc).

If any chart shows an error ("Configuration incomplete," "Failed to fetch data," etc.), the connection is broken. Most common cause: GA4 viewer access was revoked on the underlying property.

Open GA4 in a separate tab → Reports → Acquisition → User acquisition. Set date range to Last 28 days (matching your Looker Studio report).

Note the Total users count in GA4.

Switch to Looker Studio. The Total users scorecard should be within 1-3% of GA4. Anything beyond suggests sampling, threshold filtering, or a wrong property selection.

Repeat with Sessions. Then with one specific channel row (e.g., google / organic Sessions).

Document the reconciliation in a Methodology page or a note in your team's shared doc. If numbers ever drift later, this baseline tells you what changed.

Sampling happens when GA4 estimates results from a subset of data instead of all data. It's normal for date ranges over 60 days or queries with many dimensions.

Look for the yellow shield icon at the top-right of a chart. Hover for sampling rate (e.g., 'Based on 38% of sessions').

For sampled charts: reduce the date range (Last 28 days rarely samples; Last 90 days often does), drop a dimension, or use the GA4 native UI for exact-match reporting on small slices.

For mission-critical exact numbers (revenue reconciliation, board reports), connect Looker Studio to BigQuery export of GA4 instead of the GA4 connector. Unsampled, but adds a per-query BigQuery cost.

Document any sampled charts on the report itself — add a text note like "Dimensions exceed 10K combinations; sampling applies to this chart." Honest dashboards stay trusted.

Open Resource → Manage added data sources. You should see one entry, named clearly (e.g., "GA4 — Acme.com"), with credentials matching your intent.

If you see two GA4 entries — one named and one with a generic name — you accidentally created an embedded source while building. Delete the embedded one and reconnect charts to the named source.

Click Share (top-right). For client dashboards, use email-based sharing only. For internal team dashboards, "Anyone with the link" within your Workspace domain is fine.

Send the share link to one stakeholder first. Confirm they can open it without errors. Only then broadcast to the team.