The Complete Guide to Area Charts

Catty AI

Content Writer @ ChartGG

Area charts are powerful visualization tools that combine the trend-tracking capabilities of line charts with filled areas to represent volume or magnitude. They're particularly effective at showing cumulative totals, part-to-whole relationships, and emphasizing the scale of changes over time.

Understanding Area Charts

Area charts are variations of line charts where the space between the line and the axis is filled with color or patterns. They come in several forms:

Basic Area Charts

The simplest form of area chart shows a single data series with the area below the line filled. These charts are excellent for displaying volumes, totals, or cumulative values over time. Common applications include showing total sales volume, website traffic, or market size evolution.

Stacked Area Charts

These charts display multiple data series stacked on top of each other, with each series represented by a different colored area. They're perfect for showing how different components contribute to a total while tracking changes over time. For example, showing revenue breakdown by product categories or market share distribution among competitors.

100% Stacked Area Charts

Similar to stacked area charts, but the values are normalized to show percentages rather than absolute values. This makes them ideal for displaying relative proportions and how they change over time, such as showing the percentage breakdown of expenses or market share distribution.

Streamgraphs

A more sophisticated variation of stacked area charts where the baseline is not fixed to the x-axis but rather curves to create a more organic, flowing appearance. They're particularly effective for visualizing large datasets with multiple categories, such as music streaming trends or social media engagement patterns.

When to Use Area Charts

Area charts are particularly effective in specific scenarios:

Showing Cumulative Totals

Area charts excel at displaying accumulated values over time. Whether you're tracking total revenue growth, cumulative project costs, or aggregate user signups, the filled area provides a strong visual representation of accumulation and growth.

Visualizing Part-to-Whole Relationships

Stacked area charts are perfect for showing how different components contribute to a total while maintaining the context of the overall volume. They help answer questions about both absolute values and relative proportions simultaneously.

Emphasizing Volume and Magnitude

The filled area in these charts creates a strong visual impact that emphasizes the scale and magnitude of data. This makes them particularly effective for showing significant volumes or when you want to draw attention to the size of changes over time.

Displaying Composition Changes

100% stacked area charts are ideal for showing how the composition of a whole changes over time. They're perfect for visualizing market share evolution, budget allocation changes, or demographic shifts.

Best Practices for Area Charts

To create effective area charts, follow these guidelines:

Color Selection

• Choose colors that provide good contrast and are visually distinct
• Use a logical color progression for related categories
• Consider color opacity to prevent visual overwhelming in stacked charts
• Ensure accessibility by selecting colorblind-friendly palettes

Data Organization

• Order stacked areas logically, typically placing less volatile series at the bottom
• Limit the number of categories in stacked charts to maintain readability
• Consider using small multiples for complex comparisons instead of overcrowding a single chart

Scale and Baseline

• Always start the y-axis at zero for area charts to avoid misrepresentation
• Use consistent scales when comparing multiple charts
• Consider using log scales for data with large value ranges

Clarity and Readability

• Add clear labels and legends
• Include gridlines for easier value reading
• Use interactive tooltips for detailed information
• Avoid overlapping labels and ensure text is readable

Common Pitfalls to Avoid

Overcomplication

Don't try to show too many categories in a single stacked area chart. Too many layers can make the chart difficult to read and interpret. If you have many categories, consider using small multiples or focusing on the most significant categories.

Poor Color Choices

Avoid using colors that are too similar or that create visual vibration when adjacent. This is particularly important in stacked area charts where colors need to be clearly distinguishable.

Misleading Scales

Never truncate the y-axis in an area chart as this can create misleading impressions of the data magnitude. Always start from zero to maintain proper proportional representation.

Overlapping Transparency

Be cautious with transparency in overlapping areas, as it can create confusing color combinations and make the chart harder to interpret.

Interactive Features

Modern area charts can benefit from interactive elements:

Hover Effects

• Show detailed data points on hover
• Highlight specific areas or series when moused over
• Display additional context or metadata in tooltips

Zoom and Pan

• Allow users to zoom into specific time periods
• Enable panning to explore different time ranges
• Provide reset options to return to the original view

Filtering

• Enable toggling of different data series
• Allow users to focus on specific categories
• Provide options to switch between different views (stacked, 100% stacked, streamgraph)

Conclusion

Area charts are versatile tools for data visualization that combine the trend-tracking abilities of line charts with the volume emphasis of filled areas. When used appropriately and following best practices, they can create compelling and informative visualizations that effectively communicate your data story.

Whether you're showing cumulative growth, analyzing market share changes, or displaying resource allocation over time, area charts can help you create clear and impactful data presentations. Remember to keep your charts simple, choose appropriate colors, and maintain clear labeling to ensure your message is effectively conveyed to your audience.