What is a Line Chart in Tableau?

A line chart is one of the most fundamental and powerful tools for telling a story with your data. In Tableau, it's the go-to choice for visualizing changes, spotting patterns, and understanding performance over a specific period. This article will walk you through what a Tableau line chart is, when to use it, and exactly how to build one step-by-step.

What is a Line Chart?

At its core, a line chart (or line graph) is a type of chart that displays information as a series of data points called 'markers' connected by straight line segments. It's incredibly intuitive. The vertical y-axis almost always represents a quantitative value (like sales, revenue, or website traffic), while the horizontal x-axis typically represents a continuous dimension, most often time (like days, months, quarters, or years).

The beauty of the line chart lies in its simplicity. By connecting the dots, you can immediately see the "shape" of your data over time. You can quickly answer questions like:

• Is our revenue growing, declining, or staying flat?
• Did our website traffic spike after we launched that ad campaign last week?
• Are there seasonal patterns in our product sales, like a dip in the summer or a rush during the holidays?

The continuous line implies a connection between the data points, making it the perfect vehicle for illustrating trends, acceleration, deceleration, and volatility.

When a Line Chart is Your Best Option

While versatile, line charts are not a one-size-fits-all solution. They excel in specific situations, particularly when you need to show continuity and progression. Here are the most common and effective use cases for a line chart in Tableau.

Tracking a Single Metric Over Time

This is the classic use case. You have one key performance indicator (KPI), and you want to see how it has performed over a period. This is perfect for high-level dashboard summaries where you want to show the overall health of a specific business function.

Examples:

• Tracking monthly sales revenue for the past two years.
• Visualizing daily active users on your app for the last 30 days.
• Monitoring week-over-week website sessions from organic search.

Comparing Trends Across Different Categories

Line charts become even more insightful when you overlay multiple lines on the same graph. By using different colors or patterns to represent different categories, you can directly compare their performance over the same time frame.

Examples:

• Comparing the sales growth of three different product categories (e.g., Furniture, Office Supplies, Technology) quarter-over-quarter.
• Showing the website traffic trends across different marketing channels (e.g., SEO, Paid Social, Email) each month.
• Analyzing customer acquisition cost (CAC) for different regions (e.g., North America, EMEA, APAC) over time.

Identifying Seasonality and Outliers

Because line charts show data continuously, they are excellent for spotting recurring patterns or "seasonality." If you see a similar peak every December, you've identified a holiday sales rush. If you see a consistent dip every weekend, that's a pattern in your B2B business cycle. Likewise, sudden spikes or dips that break the pattern (outliers) are immediately visible, prompting you to investigate the cause.

How to Create a Line Chart in Tableau

Creating a basic line chart in Tableau is a simple drag-and-drop process. Let's build one using a common scenario: visualizing monthly sales. For this example, imagine you have a simple spreadsheet with columns like Order Date and Sales.

Step 1: Connect to Your Data

First, open Tableau and connect to your data source, whether it's an Excel file, a CSV, or a database. Once connected, your data's columns will appear in the "Data" pane on the left, organized into Dimensions (categorical data like dates, names, or regions) and Measures (numerical data like sales, profit, or quantity).

Step 2: Add Your Time Dimension to Columns

A line chart needs a time axis. Find your date field (in our case, Order Date) in the Dimensions pane and drag it onto the Columns shelf at the top of the workspace. By default, Tableau will likely aggregate this by YEAR(Order Date).

Step 3: Add Your Measure to Rows

Next, you need to plot a value against that time axis. Find your measure (in our case, Sales) in the Measures pane and drag it onto the Rows shelf. Tableau will automatically plot the SUM(Sales) for each year and - voila - you'll see a basic line chart appear.

Step 4: Adjust the Granularity of Your Date

A yearly view might be too high-level. To get a more detailed trend, you can easily change the date granularity. Right-click the YEAR(Order Date) pill in the Columns shelf. You’ll see options to drill down to Quarter, Month, Week, or Day.

Choose Month from the dropdown. It’s important to select the option in the second section (e.g., Month May 2020) rather than the first section (e.g., Month May). The first option gives you a discrete date part (every "May" combined), while the second gives you a continuous date line, which is what we want for a time-series trend.

Your chart will now update to show a more detailed monthly sales trend.

Pro Tips for Enhancing Your Line Chart

Getting a basic line chart on the screen is just the start. With a few extra steps, you can make your visualization far more insightful.

1. Use Color to Compare Categories

To compare different categories on the same chart, find a categorical dimension (like Region or Product Category) and drag it onto the Color tile in the Marks card. Tableau will instantly create a separate, color-coded line for each category, along with a handy legend.

This is the fastest way to see which product lines are driving growth or which regions are underperforming.

2. Create a Dual-Axis Chart to Show Two Different Measures

What if you want to track two different measures, like Sales and Profit, on the same chart? Their scales might be wildly different, which can be misleading on a single axis. The solution is a dual-axis chart.

• Start with your existing SUM(Sales) line chart.
• Drag your second measure (e.g., Profit) onto the Rows shelf, to the right of your first measure. You will now have two separate line charts.
• Right-click the second measure pill (SUM(Profit)) in the Rows shelf and select Dual Axis from the menu.

Tableau will merge the two charts, giving each measure its own y-axis. You can now clearly see the relationship between sales and profit over time. Just be sure to use different colors for each line for clarity!

3. Add Markers, Labels, and Tooltips

Sometimes the line alone isn't enough. You can enhance it in several ways using the Marks card:

• Markers: Click the "Color" tile, select Markers, and choose a style. This adds a dot to each data point, making specific values easier to identify.
• Labels: Drag your Sales measure from the Measures pane onto the "Label" tile. This will display the exact value at each point on the line. Use this sparingly, as it can quickly clutter your chart. It's often better to label just the minimum and maximum points.
• Tooltips: Hover over any point on your line, and you'll see a tooltip with its details. You can customize what appears here by clicking the "Tooltip" tile and editing the text. You can add more information, like Profit or Quantity, by dragging those fields onto the Tooltip tile.

4. Format for Clarity

Finally, always clean up your chart for your audience:

• Give your chart a clear, descriptive title (e.g., "Monthly Sales Trend by Product Category").
• Make sure your axis labels are clear and include units (like $, €, etc.).
• Adjust colors to match your company's branding or to draw attention to a specific line.
• Use annotations to call out significant events (right-click a point on the chart and select "Annotate" -> "Point"). For example, you could add a note like "Launched Summer Ad Campaign" to explain a sudden sales spike.

Final Thoughts

The line chart is a fundamental building block of data visualization, and mastering it in Tableau is a crucial skill for any analyst. It’s the simplest way to show trends over time, providing immediate insight into performance, patterns, and outliers by dragging a date to columns and a measure to rows.

While tools like Tableau offer powerful drag-and-drop interfaces, sometimes even that process can feel slow when you just need a quick answer. That's why we built Graphed to be even faster. Instead of clicking and dragging, you can simply ask in plain English, "Show me monthly sales over the last two years as a line chart," and instantly get a live, interactive visualization. It's designed to make data exploration as easy as a conversation, allowing anyone on your team to get insights in seconds, not minutes.