Line Chart

Line charts are great to show the evolution of 1 or several values over time. They are useful for spotting trends and can be used to infer the correlation between 2 or more categories.

Usage guidelines

When to use

Questions you can answer

• How has this category value changed over time?
• What is the trend for this category?

When not to use

• Line charts are most useful to display trends. Depending on what you want to highlight, other charts that can help show variance over time are the area chart and the box plot chart.
• If you have a large number of categories, consider a sparklines chart.

Usage recommendations

Make sure the time intervals are equal, otherwise the trend would be distorted.

Using more than 3 categories can make it difficult to identify individual trends. Consider a sparklines chart instead.

Use consistent categories, for example, compare the number of sales from different departments, instead of sales and department size.

If you do compare different categories, for example, sales and opportunities, make sure they have a similar scale. Otherwise, the chart won't provide useful information.

Don't use always a zero-value baseline. The goal of a line chart is to show changes in value. If a 0 baseline doesn't provide meaningful information, it's ok to zoom in on the vertical axis. But this is an editorial decision, and it must be clear to the reader that the vertical axis is truncated.

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