Line chart: definition, examples, and best practices.

What is a line graph?

A line graph plots values along a continuous axis, usually time, and connects consecutive points with a line. That connecting line is what separates it from a bar chart: it implies continuity between points, which makes it well suited to anything that moves smoothly rather than sitting in discrete, unrelated categories.

The type is also called a line chart or a trend chart. Whichever name is used, the core idea stays the same: one continuous axis, one or more series, and the shape of the line carries the message.

A worked example

All-in remittance spread by corridor, as a percentage of principal, from January 2024 to April 2025. Spreads compress about 25% across the board, but EUR to XOF stays a 10.8% outlier, which is why the chart carries an axis break. Five of nine corridors shown.

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When to use a line graph

• Tracking revenue, costs or margin over months or quarters, the backbone of most FP&A dashboards.
• Comparing several indexed metrics over the same period to see which one is pulling ahead or falling behind.
• Plotting a forecast against actuals to show whether the current trajectory is on track against a target.
• Monitoring an operational metric, like daily active users or response time, to catch anomalies as they happen.

When not to use a line graph

• If cumulative volume matters as much as the trend, an area chart makes that volume visible.
• If your categories are not naturally sequential, use a clustered bar chart instead of forcing a line through unrelated groups.

How to read a line graph

Follow each line from left to right and focus on its slope, not just its endpoint. A steep upward slope means fast growth, a flat line means a plateau, and a downward slope means decline. When lines cross, that crossover point usually marks a meaningful shift worth calling out directly on the chart.

Best practices

• Cap the number of lines at four or five. Beyond that, the chart turns into a tangle that no color scheme can fully rescue.
• Label each line directly at its end point rather than relying on a separate legend, so the eye never has to jump back and forth.
• Keep time intervals evenly spaced. Mixing monthly and quarterly points on the same axis distorts the visual slope.
• Annotate significant events directly on the chart, a pricing change or a launch, so the reader has context for a sudden move.
• Use a consistent color for the same metric across every chart in a deck, so the reader does not have to relearn the legend each time.