The Complete Guide to Area Charts & Volume Graphs

What is an Area Chart?

An area chart (or area graph) is a quantitative graphic based on the line chart. In an area chart, the space between the plotted line trajectory and the horizontal baseline (typically $Y = 0$) is filled with colors, textures, or translucent gradients.

While a standard line graph emphasizes the rate of change and directional slope between discrete points, an area chart emphasizes the volume and magnitude of a metric over time. The filled area gives visceral weight to accumulated quantities, such as total electricity consumed, data transferred across networks, or water reservoir capacities.

Mathematical Foundations: Area Under the Curve & Trapezoidal Integration

In calculus and numerical analysis, calculating the total shaded volume beneath an area chart represents computing the definite integral of the function $f(x)$ between bounds $a$ and $b$:

Area Chart vs. Line Graph: When to Use Which?

Best Practices for Designing Accurate Area Charts

• Always maintain a zero baseline ($Y = 0$): Because viewers interpret the shaded area as total quantity, cutting off the bottom of the axis distorts the perceived volume.
• Use translucent gradients: Subtle vertical gradients that fade towards the bottom maintain visual elegance without overwhelming grid lines and coordinate markers.
• Avoid overlapping multiple opaque layers: If plotting multiple series, use stacked area charts or distinct line graphs to prevent background series from being occluded.