Area Chart

An area chart is a line chart with the region between the line and the axis filled in with color. The line still shows the trend, but the shaded area draws the eye to the magnitude or volume beneath it — useful when the size of a quantity matters as much as its direction. Area charts work best for continuous data over time (revenue by month, sessions by day) and can be stacked to show how parts contribute to a whole.

Use an area chart when the volume or cumulative size of the values is part of the story — total revenue, total sessions, total spend over time — and you want that magnitude to feel substantial. Use a plain line chart when you only care about the trend direction or need to compare several series precisely, because filled areas can occlude one another and make exact values harder to read. A good rule of thumb: one or two series where volume matters → area; three or more series you need to compare point-for-point → line.

A standard (overlapping) area chart plots each series from the same zero baseline, so series can overlap and you read each one against the axis. A stacked area chart places each series on top of the one below it, so the top edge shows the combined total and each band shows that series' contribution to the whole. Stack when you want part-to-whole over time (e.g. revenue by channel summing to total revenue); avoid stacking when you need to read each series' exact value, because only the bottom band starts at zero.

Three to watch: (1) Overlap — with more than two or three overlapping series, fills hide each other; use transparency or switch to lines. (2) Misreading stacked values — in a stacked area chart only the bottom series sits on the zero baseline, so the others are easy to misjudge. (3) Wrong data type — area charts imply continuity, so they suit time series and sequential data, not unordered categories (use a bar chart there). Keep to 3–5 series and label clearly.

Continuous, ordered data — most often a time series — with one or more numeric values per point: revenue or cost by month, daily active users, traffic volume by week, ad spend over a campaign. You need at least two points to show change, consistent intervals between points, and ideally no more than 3–5 series so the fills stay legible. For part-to-whole over time, stack the series; for a single trend where volume matters, a single filled area is cleanest.