How to Create a Stacked Bar Chart in Looker

A stacked bar chart can instantly show you not just your overall performance but also the individual pieces that make up that total. Instead of guessing how different channels contribute to your web traffic or which product categories make up your quarterly sales, you can see it all in one clear visual. This guide will walk you through exactly what a stacked bar chart is, when to use it, and how to build one step-by-step in Looker Studio.

What Exactly Is a Stacked Bar Chart?

A stacked bar chart is a type of graph that uses bars to compare totals across different categories while also showing the composition of each total. Think of it as a standard bar chart that’s been sliced into segments. Each main bar represents a total value, and the different colored segments inside that bar represent the individual parts or sub-categories that add up to that total.

For example, a regular bar chart might show you your total website sessions for January, February, and March. A stacked bar chart would show you those same monthly totals, but each monthly bar would be segmented to show you how much of that traffic came from Organic Search, Paid Social, Direct, and Email.

These charts can be arranged in two ways:

• Stacked Column Chart (Vertical): Bars go up and down. This is the most common format and works well for showing changes over a time series, like month over month.
• Stacked Bar Chart (Horizontal): Bars go from left to right. This format is great when you have long category labels that are easier to read horizontally.

The core benefit is its efficiency. It lets you make two kinds of comparisons at once: you can compare the overall totals (the full length of the bars), and you can see the internal composition of each of those totals simultaneously.

When Should You Use a Stacked Bar Chart?

Stacked bar charts are incredibly versatile, but they shine brightest in specific situations. Here’s when you should consider using one.

1. To Show Part-to-Whole Relationships Over Time

This is the classic use case. When you need to see how the mix of different components changes from one period to the next, a stacked bar chart is an incredibly effective choice. It quickly answers questions like, "Did our Organic Search traffic grow as a proportion of total traffic this quarter compared to last?"

Example: A marketing manager wants to track monthly revenue broken down by campaign source (e.g., Google Ads, Facebook Ads, Newsletter). A stacked bar chart would not only show if total revenue is growing each month but also whether certain campaigns are becoming more or less important to that total.

2. To Compare Composition Across Different Categories

You don't always need a time-based axis. Stacked bar charts are also great for comparing the makeup of static categories. This helps you understand structural differences between them.

Example: An e-commerce brand wants to compare the sales composition of different product lines. They can create a bar for "Apparel," "Accessories," and "Footwear." Each bar is then stacked by the region of sale (North America, Europe, Asia), showing which regions contribute most to each product line's total sales.

3. To Visualize Survey or Polling Data

Stacked bar charts are perfect for visualizing responses to survey questions, like Likert scales (e.g., Strongly Agree, Agree, Neutral, Disagree, Strongly Disagree). Each bar can represent a different question or demographic group, and the segments show the proportion of each response.

Example: A product team surveyed customer satisfaction for three different features. A stacked bar chart can show the total number of responses for each feature, with segments representing "Very Satisfied," "Satisfied," "Neutral," and "Dissatisfied." This gives a quick visual summary of which features are most and least popular.

When to Avoid Using a Stacked Bar Chart

While powerful, stacked bar charts aren’t a one-size-fits-all solution. Using them in the wrong context can lead to confusing and misleading visualizations. Here are a few scenarios where you're better off choosing a different chart type.

• When You Need to Precisely Compare Segments: In a stacked chart, only the bottom-most segment of each bar shares a common baseline (zero). All other segments start at different points, making them very difficult to compare accurately. If your primary goal is to compare the performance of individual email campaigns against each other (not their total), a grouped bar chart is a much better choice.
• When You Have Too Many Segments: Once you add more than about five or six segments to each bar, the chart becomes a cluttered, unreadable rainbow. It’s hard to distinguish colors and compare the smaller segments. In this case, consider grouping smaller categories into an "Other" category or using a treemap.
• When Categories Don't Sum to a Meaningful Whole: The central idea of a stacked chart is that the segments add up to a logical total. If the metrics you're plotting don't represent a true part-to-whole relationship (e.g., stacking Website Sessions and Bounce Rate), the chart will be nonsensical.

How to Create a Stacked Bar Chart in Looker Studio: A Step-by-Step Guide

Ready to build your own? Let's walk through creating a stacked column chart in Looker Studio using data from Google Analytics 4. Our goal is to visualize website sessions by month, broken down by device category (Desktop, Mobile, Tablet).

Step 1: Connect Your Data Source

First things first, you need data. For this example, we’ll assume you’ve already connected a Google Analytics 4 data source. If you haven't, you can do so by going to Resource > Manage added data sources > Add A Data Source and selecting "Google Analytics."

If you don’t have GA4, you can use any data source that has at least two dimensions and one metric. For instance, a Google Sheet with columns for "Month" (dimension), "Region" (breakdown dimension), and "Sales" (metric) would work perfectly.

Step 2: Add a Stacked Chart to Your Report

Once you're in your Looker Studio report canvas, navigate to the toolbar at the top.

1. Click on “Add a chart.”
2. In the dropdown menu, find the “Bar” section.
3. Select either the “Stacked bar chart” (for a horizontal layout) or the “Stacked column chart” (for a vertical layout). We’ll use the stacked column chart for this tutorial.
4. Click on the canvas to place your new, unconfigured chart. Looker Studio will populate it with default dimensions and metrics from your data source.

Step 3: Configure the Chart’s Data Tab

With your new chart selected, the configuration panel will appear on the right side of the screen. This is where you tell Looker Studio how to build your visual. Make sure you’re on the “SETUP” tab.

Here’s how to set it up:

1. Set the Dimension:

This is the primary category that will be displayed on the x-axis. It defines what each bar represents.

• Under the “Dimension” field, let's use a time-based dimension. Find and select “Date.”
• To group our data monthly, hover over the pencil icon next to "Date" to edit it. Go to Type > Date & Time > Month. Now, your x-axis will show months instead of individual days.

2. Set the Breakdown Dimension:

This is the dimension that will slice each bar into segments. This is what makes it a stacked chart.

• Under the “Breakdown Dimension” field, click and add the dimension “Device Category.” This will create segments for Desktop, Mobile, and Tablet within each monthly bar.

3. Set the Metric:

This is the numerical value you want to measure. The height of the bar segments will be based on this value.

• Under the “Metric” field, select "Sessions".

Just like that, your chart should now be correctly displaying monthly sessions broken down by device type!

Step 4: Customize Your Chart in the Style Tab

Your chart is functional, but let's make it look great and easy to read. Click the "STYLE" tab in the right-hand panel.

Here are a few common customizations:

• Colors: You can assign specific colors to your segments. Under "Bar Colors," feel free to change the default palette to match your company's branding or to create a more intuitive color scheme.
• Data Labels: To show the exact number for each segment, scroll down and check the box for “Show data labels." This places the value directly on the chart, which means your viewers don’t have to guess or refer to the y-axis.
• Legend: The legend tells viewers what each color represents. You can change its position (top, bottom, right, or none) and customize its font under the "Legend" section. Setting it to the top or right is usually best for readability.
• Axes: Under "Axes," you can turn on "Show axis titles" to label your X and Y axes (e.g., “Month” and “Total Sessions”). You can also adjust font sizes and colors.
• Grid: Change the grid color or remove the grid lines entirely for a cleaner look under the "Grid" section. Often, a subtle, light-grey grid is all you need.

Pro-Tips for Exceptional Stacked Bar Charts

Building the chart is just the beginning. Follow these tips to make sure your visualizations are effective and insightful.

Know When to Use the "100% Stacked" Variation

In the "STYLE" tab, there's an option called "Show as 100% stacked." This transforms your chart so that every bar fills the full height to 100%. The segments now show the percentage makeup of each bar rather than the absolute value. This is extremely useful when your primary goal is to compare the relative composition of categories, especially if their total values are wildly different.

Order Your Segments Logically

The order of segments in your stacks can influence how people interpret the data. For better readability, consider arranging the breakdown dimension in a logical way from the “SETUP” tab. You can sort by name or by a metric. Consistency is helpful for pattern recognition.

Be Consistent With Colors

If you're using color to represent categories like "Desktop," "Mobile," and "Tablet," use those same colors for those categories across your entire dashboard. This creates a cohesive visual language that helps your audience understand new charts fast and effectively, without needing to constantly re-check the legend.

Final Thoughts

The stacked bar chart is a go-to tool for any data-driven professional. It excels at showing how individual components contribute to a whole, especially over time. By following the steps above, you can confidently create clear, insightful, and customized stacked bar charts in Looker Studio that tell a compelling story about your data.

While Looker Studio is powerful, getting your report just right can still take time digging through menus and configuring dimensions. Sometimes you just need to answer a business question without becoming a data viz expert. At Graphed, we’ve simplified the entire process. Rather than clicking through setup panels, you can connect your data sources and create reports just by asking questions in plain English, like "Show me a stacked bar chart of traffic by channel for the last six months." We handle the setup and visualization instantly, turning hours of configuration into minutes of conversation.