How to Use Line Chart in Power BI

A line chart is one of the most effective ways to tell a story about how data changes over time. Whether you're tracking monthly sales, website traffic, or project progress, a well-made line chart brings trends to life. This guide will walk you through exactly how to create, customize, and elevate line charts in Power BI to make your data clear and impactful.

What is a Line Chart and When Should You Use It?

At its core, a line chart plots data points on a graph and connects them with a single line. This simple concept is incredibly powerful for visualizing data over a continuous interval, making it perfect for spotting trends, patterns, cycles, and anomalies.

The horizontal (x-axis) of a line chart typically represents a time period - like days, months, quarters, or years - while the vertical (y-axis) represents a quantitative measurement.

You should reach for a line chart whenever you want to answer questions like:

• How has our revenue grown over the past three years?
• What are the daily fluctuations in our website’s user sessions?
• Are support ticket volumes increasing or decreasing month over month?
• Which marketing campaign generated the most leads CPL over its duration?

Essentially, if your goal is to show a progression or trend, the line chart is your best friend. In contrast, avoid using it to compare static, categorical data where the order doesn't matter, like sales by product category - a bar chart would be a better fit for that scenario.

How to Create a Line Chart in Power BI: A Step-by-Step Guide

Creating your first line chart in Power BI is a straightforward process. Let’s assume you’ve already loaded some data into Power BI Desktop. We'll use a simple sales dataset containing columns for OrderDate, SalesAmount, and ProductCategory.

Step 1: Open Your Report and Select the Visual

Start with a blank canvas on your Power BI report. In the Visualizations pane on the right-hand side, find and click the line chart icon. An empty line chart template will appear on your report canvas.

Step 2: Add Your Data Fields

With the empty visual selected, you'll see several fields in the Visualizations pane: X-axis, Y-axis, Secondary y-axis, and Legend. This is where you tell Power BI what data to plot.

• For the X-axis: This field is for your time dimension. Drag your OrderDate column from the Data pane and drop it into the X-axis field. Power BI is smart about dates and will automatically create a date hierarchy (Year, Quarter, Month, Day) for you.
• For the Y-axis: This is for the value you want to measure. Drag your SalesAmount column and drop it into the Y-axis field.

Instantly, Power BI will generate a line chart showing your total sales over time. Initially, it might show the data by year. We’ll cover how to change that in a bit.

Step 3: Add a Legend to Compare Categories

A single line showing total sales is useful, but what if you want to compare sales across different product categories over the same period? This is where the Legend field comes in.

Drag the ProductCategory column from your Data pane into the Legend field. Power BI will instantly create separate, color-coded lines for each product category on your chart. You can now easily compare the performance of each category side-by-side.

Step 4: Use the Drill-Down Feature

Earlier, we mentioned Power BI’s automatic date hierarchy. Now, it's time to use it. When you first plot your data, you might see the trend by year. In the top-right corner of the visual, you'll see several arrow icons. These control the drill-down functionality.

• Drill Down button (arrow facing down): Click this to turn on drill mode. Now, if you click on a specific year on your chart (e.g., "2023"), the chart will update to show you the data broken down by quarter for that year. Click a quarter, and you'll see the months.
• Go to the next level button (double arrow facing down): Click this to expand the entire chart to the next level in the hierarchy uniformly. For example, clicking it once will change the view from years to quarters for all years on the chart.

Experimenting with these is the key to exploring your data at different levels of detail right from the visual itself.

Making Your Line Chart Shine: Formatting Tips

A functional chart is great, but a well-formatted one is even better. It makes your data easier to read and understand at a glance. To start formatting, select your chart and click the paintbrush icon ("Format your visual") in the Visualizations pane.

Customize the X and Y Axes

Under the Visual tab, you’ll find options for both the X-axis and Y-axis.

• Title: You can edit or disable the axis titles. By default, they’re named after your data columns, but you might want to simplify them (e.g., change "Sum of SalesAmount" to "Total Sales").
• Values: Change the font, size, and color of the axis labels for better readability.
• Range (Y-axis only): Set a manual minimum and maximum for the y-axis to control the scale and better emphasize certain changes in the data.

Modify Lines and Markers

In the "Lines" section, you can customize the appearance of each data series.

• Colors: To change line colors, go to the Lines section and expand the Colors dropdown. You can assign colors that match your company's branding or make certain categories stand out.
• Stroke width: Make lines thicker or thinner to adjust their visual weight.
• Style: Change the line style from Solid to Dashed or Dotted to differentiate certain lines, like a forecast versus actual data.

In the "Markers" section, you can add visual points for each data entry on the line, which can make it easier to see specific data points. Toggle this on and you can customize their shape (circle, square, diamond), size, and color.

Improve The Title and Legend

• Title: Under the General tab, you can edit the main chart title. Make it descriptive and concise. For example, "Monthly Sales Trend by Product Category." Adjust the font, size, and alignment here as well.
• Legend: Found in the Legend section under the Visual tab, you can move the legend's position (e.g., Top center, Bottom right) or change its text formatting. If your chart only has one line, consider turning off the legend to save space.

Turn on Data Labels

For charts where viewers need to know the exact values, turn on Data labels. This will display the numeric value next to each data point on the line. You have granular control over the font, display units (e.g., thousands, millions), and positioning of these labels to keep your chart from looking cluttered.

Level Up Your Line Charts: Advanced Techniques

Once you are comfortable with the basics, Power BI offers powerful analytics features to get even more insights from your line charts directly from the Visualizations pane by clicking the magnifying glass icon ("Add further analysis to your visual").

Adding a Trend Line

A trend line helps you visualize the overall direction of your data, smoothing out the noise of day-to-day fluctuations. Under the Analytics pane, find the Trend line option and click + Add. Power BI will automatically draw a line that shows the general direction your data is moving - upward, downward, or flat.

Creating a Forecast

Want to predict future sales based on past performance? Power BI’s forecasting feature does this in just a few clicks.

In the Analytics pane, find the Forecast section.

• Turn the forecast on.
• Set the Forecast length (e.g., 3 Months).
• Adjust the Confidence interval to control how wide the range of possible outcomes is (a 95% confidence interval is standard).

Power BI will extend your time series into the future, showing you the projected trend along with an upper and lower bound - super useful for planning and goal-setting.

Adding a Secondary Y-Axis

What if you want to plot two metrics with very different scales on the same chart, like sales revenue (in the millions) and units sold (in the thousands)? If you plot these on the same Y-axis, the units sold line would look almost completely flat.

The solution is a combo chart. Start by selecting the "Line and stacked column chart" from the Visualizations pane.

• Place your OrderDate on the X-axis.
• Place your SalesAmount on the Column y-axis.
• Place your UnitsSold metric right on the Line y-axis, and another line corresponding with UnitsSold will appear above the bar chart.

This allows you to compare two different kinds of metrics that follow the same x-axis at the same time in the same visualization.

Final Thoughts

You now have a solid foundation for creating, formatting, and using Power BI's advanced features for your line charts. The line chart is a fundamental tool for any creator of data visualizations, and Power BI makes creating robust, professional ones easy for your audience, helping them to unlock trends and insights from your organization’s data.

While tools like Power BI are incredibly powerful, they still come with a learning curve and require time to manually build and format each report. With Graphed, we decided to automate the busy work. Instead of clicking through menus, you can simply ask in plain English, "Show me a line chart of Shopify sales vs. Facebook Ad spend over the last quarter," and instantly get a live, interactive visualization. We connect directly to your data sources, allowing you to ask questions and get answers in seconds, not hours.