How to Make a Bar Graph in Looker

Creating a bar graph in Looker is one of the most fundamental ways to visualize your data, transforming rows of numbers into a clear, comparable story. This guide will walk you through the entire process, from selecting your data in an Explore to customizing your visualization for maximum clarity.

Why Use a Bar Graph in the First Place?

Before we jump into the "how," let's quickly cover the "why." Bar graphs are perfect for one main job: comparing values across different categories. They excel at showing the "how much" or "how many" for distinct groups, making it easy to spot high and low performers at a glance.

Some common use cases for bar graphs include:

Tracking sales performance by product category.
Comparing website traffic from different marketing channels.
Showing the number of support tickets assigned to each team member.
Visualizing customer counts by region or country.

In short, if you have categorical data (like product names, regions, or marketing channels) and you want to compare their numeric values (like sales, users, or ticket counts), a bar graph is your best friend.

Getting Started: Understanding the Looker Explore Interface

Everything in Looker starts in an Explore. Think of an Explore as a curated dataset designed for a specific area of your business, like "Orders," "Website Traffic," or "Users." When you open an Explore, you'll see a list of fields on the left, split into two crucial types:

Dimensions: These are the "grouping" fields, often text-based. They are your categories. Think Product Category, Traffic Source, User Country, or a date like Created Month. Looker colors dimensions blue.
Measures: These are the numeric values you want to calculate or aggregate, like a count, sum, or average. Think Total Sales, Order Count, or Average Session Duration. Looker colors measures orange.

The core concept of building any visualization in Looker is simple: pick at least one dimension to group by and one measure to calculate for each group.

Step-by-Step: Creating Your First Bar Graph

Let’s build a common report: Total Revenue by Traffic Source. This will help us understand which marketing channels are driving the most sales.

Step 1: Choose Your Dimension and Measure

First, navigate to the correct Explore. For this example, let's assume we're in an Explore that merges website traffic data with sales data.

In the fields list on the left, find your dimension. We'll search for "Traffic Source" and click on it. It will be added to the Data section on the right.
Next, find your measure. Search for "Total Revenue" and click on it. It will also appear in the Data section.

Your Data section should now show two selected fields: one blue (Dimension) and one orange (Measure).

Step 2: Run the Query

With your fields selected, click the "Run" button in the top right corner. Looker retrieves the data and presents it in a table below the Data section. You’ll see a list of traffic sources and the total revenue associated with each one.

Step 3: Select the Bar Chart Visualization

The table is useful, but a bar graph will make the comparison instant. Directly below the "Run" button, you'll see a Visualization tab. Click it.

Looker will automatically suggest a visualization, but you can choose the one you want from the plot style icons. Click on the Bar chart icon (the one with horizontal bars). Voila! You now have a bar graph showing your total revenue across traffic sources.

Customizing Your Looker Bar Graph

A basic graph is good, but a well-customized graph is great. Looker’s visualization editor (accessed via the "Edit" button in the Visualization tab) offers a ton of options to fine-tune your chart. Let's look at the most useful settings organized by tabs.

The "Plot" Tab

This tab controls the overall structure and feel of your chart.

Chart Type: You can switch between Bar (horizontal), Column (vertical), Scatterplot, Line, and more right from here.
Stacking: This is a powerful feature when you add another dimension. For example, if you add "Device Category" (Desktop, Mobile) to our chart, you can choose:
- Grouped: Puts bars for Desktop and Mobile side-by-side for each traffic source, which is great for direct comparison.
- Stacked: Stacks the Desktop and Mobile revenue on top of each other in a single bar for each source, showing you the part-to-whole relationship.
Swap X/Y Axis: Easily switch between a horizontal bar chart and a vertical column chart with a single click. Hot tip: horizontal bar charts work much better when you have long category names.

The "Series" Tab

Here’s where you control the look of the actual bars in your graph.

Colors: You can set a custom color palette or assign specific colors to each series (e.g., make your "Direct" traffic source always appear blue). This is great for keeping your brand colors consistent.
Customizations: This accordion menu is a treasure trove. You can change a specific series's type (e.g., turn one bar series into a line), change its color, or add labels.
Value Labels: Toggle this 'On' to display the numeric value on each bar. This is hugely helpful for readability, so users don't have to guess the exact value by looking at the axis. You can also adjust the font color and size of these labels.
Trend Line: If your x-axis is a time series, you can add a trend line to see the general direction of your data over time.

The "Values" Tab

This tab is all about how the numbers on your chart are displayed.

Value Format: This is essential! Here you can format your numbers as currency ($), percentages (%), or decimals. For our "Total Revenue" example, you’d want a format like $#,##0.00 to show it as dollars and cents.
Value Labels: Same as the setting in the Series tab. It's often included in multiple places for convenience.

The "X" and "Y" Tabs

These tabs give you full control over your chart’s axes.

Show Axis Name: Toggle this on or off to hide or show the axis titles.
Axis Name: Don’t like the default axis title pulled from the field name? Write your own custom, more descriptive name here (e.g., change "Total_Revenue" to "Total Revenue ($)").
Reversed Axis: Flip the order of the axis. By default, bar charts often show the highest value at the top, reversing it would put it at the bottom.
Logarithmic Scale: Very useful if you have a wide range of values (e.g., one category has a value of 1,000,000 and the others are below 10,000). A log scale makes variations in the smaller values more visible.

Pro-Tips for Great Bar Graphs

Getting Looker to make a chart is easy. Making a chart that communicates information effectively takes a little thought.

Sort Your Data: Always sort your bars in a logical order. Typically, this means sorting them from highest to lowest (or vice-versa) to instantly show rank. You can do this by clicking the header of the measure in the data table before opening the visualization tab.
Use Color Meaningfully: Don't just pick random pretty colors. Use color to highlight a specific category or to stick to your company's brand guidelines. A consistent, limited color palette is easier on the eyes.
Use Horizontal Bars for Long Labels: If your category names are long (like "Organic Social | Facebook / Instagram"), a vertical column chart will squish the labels, making them unreadable. Switch to a horizontal bar chart to give them plenty of space.
Keep it Simple: Don't cram too many categories or layered series into one chart. A bar chart with 50 bars is often less useful than one with the Top 10. You can limit your rows in the Data section before running the query.

Final Thoughts

Building a bar graph in Looker is a straightforward process of selecting a dimension and a measure, running a query, and then choosing the bar chart visualization. The real power comes from the deep customization options that allow you to fine-tune every aspect of the chart, ensuring your data story is clear, accurate, and easy to understand.

For many teams, the learning curve and manual clicks involved in building reports, even for simple charts, can be a constant slowdown. That's why we built Graphed_. We connect directly to your data sources, allowing you to create entire real-time dashboards just by asking questions in plain English. Instead of clicking through menus for Plots, Series, and Axes, you can simply ask, "show me a bar chart of total revenue by traffic source," and have the perfect visualization built for you in seconds.