Stacked Line Chart

Overview

A stacked line chart adds each series on top of the previous one, so the top line represents the cumulative total. Unlike stacked area, there is no fill — the focus stays on the line paths, making it easier to track individual series while still communicating the overall sum.

When to use

Show cumulative totals across departments, products, or regions
Compare both individual contributions and the aggregate trend
When area fills would be too visually heavy or distracting
Display additive components where each layer genuinely sums to the total
Communicate how each contributor's growth affects the whole

Not ideal

When individual series values are more important than their cumulative total (use basic multi-series line)
Comparing exact values of upper series (they sit on a moving baseline, just like stacked area)
Negative values without careful handling (stacking breaks the logic)
More than 5–6 series (lines become tangled)

Key variations

With or without point markers
Smoothed vs angular transitions
Percentage stacking (normalized to 100%)
Combined with subtle area fills for a hybrid look
Dashed lines for projected series

Use cases

Regional sales: Monthly revenue per region stacked to show national total
HR: Headcount growth by team stacked to show total company size
SaaS metrics: MRR broken down by pricing tier, stacked to show total MRR
Logistics: Daily deliveries by warehouse stacked to show total throughput
Energy: Electricity generation by source (solar, wind, gas) stacked to show total grid output
Education: Student enrollment by program stacked to show total university enrollment

Quick setup in Line Graph Maker

Prepare CSV with x, y, and series columns.
Upload or paste the data.
Select "Stacked Line" as chart type.
Hide point markers for cleaner look (showPoints: false).
Enable legend and tooltips for exact-value reading.
Export as PNG/SVG or share a link.

Data (CSV)

x,y,series
2025-01-01,20,Region A
2025-01-02,25,Region A
2025-01-03,28,Region A
2025-01-04,32,Region A
2025-01-05,35,Region A
2025-01-06,38,Region A
2025-01-07,42,Region A
2025-01-01,15,Region B
2025-01-02,18,Region B
2025-01-03,22,Region B
2025-01-04,25,Region B
2025-01-05,28,Region B
2025-01-06,32,Region B
2025-01-07,35,Region B
2025-01-01,10,Region C
2025-01-02,12,Region C
2025-01-03,15,Region C
2025-01-04,18,Region C
2025-01-05,20,Region C
2025-01-06,23,Region C
2025-01-07,26,Region C

Performance tips

Limit to 5–6 series for clarity; merge small contributors into "Other"
Use interactive tooltips — essential because upper-series values are hard to read visually
Consider color-coding that matches your domain conventions (e.g., warm colors for sales regions)
For presentation decks, add a single total line on top for emphasis

FAQ

Stacked line vs stacked area — when should I drop the fill? Drop the fill when the line paths themselves tell the story. Area fill emphasizes magnitude and mass; omitting it emphasizes trajectory and rate of change. In practice, stacked line is rarer than stacked area — use it when your audience is analytically literate and fills feel "too heavy."

How do I read the value of a middle series? Same as stacked area: measure the vertical gap between that series' line and the line below it. Interactive tooltips eliminate the guesswork.

Can I mix stacked and unstacked series? Yes, but carefully. You might stack three regions and overlay a separate non-stacked "target" line. Make sure the non-stacked series has a distinct visual style (dashed, different color) so readers don't confuse it with the cumulative total.

How should I order the series? Place the most stable series at the bottom (closest to the baseline) because it is the easiest to read. Put volatile or smaller series higher in the stack.

When should I use percentage stacking? Use it when share shifts matter more than absolute numbers — for example, "Did Region A's share of total sales grow?" Percentage stacking normalizes the total to 100%, removing the effect of overall growth or decline.

How do I handle a series that starts mid-way through the time range? Fill the missing early values with zero so stacking math works correctly. Optionally, use a dashed line or annotation to indicate "this series did not exist yet" to avoid implying zero contribution.

Example

Guide