Stream Chart Maker

What Is a Stream Graph?

A stream graph is a stacked area chart displaced around a central baseline, with smoothly curved edges, that shows how the composition of a total changes over time. Each flowing band is one category, and its thickness at any point is that category's value at that moment. It is also called a streamgraph, a stream chart, a river chart, or a ThemeRiver — the name from the original research that introduced it for tracking themes across document collections. This SlideModel tool builds all of them from the same data, free and in your browser.

Reach for a stream graph when the point of your slide is this turned into that. A line chart tracks each series separately, and a pie chart freezes one moment in time; a stream graph puts every category into one continuous shape so a reader takes in both the total and the mix at a glance. That makes it the natural choice for composition over time — part-to-whole data such as channel mix, revenue by segment, feature adoption, or topic popularity across years.

Why PowerPoint and Excel Can't Make a Stream Graph

Neither PowerPoint nor Excel offers a streamgraph chart type, and no add-in ships one by default. Excel's stacked area chart pins every series to a zero baseline with hard, angular corners — a different chart telling a different story. The two properties that actually define a stream graph, displacing the bands around a central axis and smoothing the boundaries between time steps, simply are not available anywhere in Office.

So the usual path is a data-visualization tool that exports a flat picture, which then cannot be recoloured to match the deck it lands in. This maker closes that gap: it produces the chart Office can't, styled for slides from the start, and with Pro it hands back a PowerPoint file whose bands are real shapes rather than a screenshot.

Stream Graph vs Stacked Area, Line, and Pie Charts

All four answer different questions from the same numbers. Picking the wrong one is the most common reason a composition slide fails to land.

Chart	Best question it answers	Baseline	Reads absolute totals	Reads the mix
Stream graph	How has the shape of this mix evolved?	Centred, floating	Poorly	Excellent
Stacked area chart	How have totals and their parts grown?	Fixed at zero	Well	Good
100% stacked (share)	How has share of total shifted?	Normalised to 100%	Not shown	Excellent
Line chart	How did each series move on its own?	Fixed at zero	Excellent	Poorly
Pie chart	What was the split at one moment?	None	Not shown	One point only

This tool builds the first three from a single dataset, so you can switch between them with one click and see which framing tells your story before committing.

How to Make a Stream Chart

1. Bring your data in. Copy a block of cells from Excel or Google Sheets and paste it into the table. Columns are your series, rows are your time steps. You can also type values by hand or start from the sample data.
2. Pick the shape. Streamgraph is the organic flowing look. Centered is a calmer symmetric silhouette. Stacked area sits on a zero baseline when absolute totals matter, and 100% normalises every step so you are reading share instead of volume.
3. Style it for your deck. Choose a palette, switch to a dark or transparent background, move between a legend and labels drawn onto the bands, and add a title.
4. Download. Take a crisp PNG for free. With Pro you can also download a vector SVG or use Insert into slide for an editable PowerPoint file.

What People Use Stream Graphs For

Marketing and growth teams chart traffic-source or channel mix month over month, where the story is organic search quietly overtaking paid — a shift that a set of separate line charts hides and one stream graph makes obvious.

Product and analytics teams show feature-usage share across releases, so a roadmap review opens with which capability users actually migrated toward rather than a table of percentages.

Finance and strategy teams present revenue by segment across quarters, using the stacked area mode when the board needs absolute totals and the 100% mode when the argument is about shifting concentration.

Researchers, journalists, and educators track topic, genre, or sentiment popularity over years. This is the chart's most famous use — the newspaper graphics of box-office performance by film that made the form recognisable — and it works equally well for citation trends or survey themes in a lecture deck.

Reading a Stream Graph Correctly

The thickness of a band is its value; its vertical position on its own is not meaningful. That is a genuine trade-off, and it is worth knowing before you choose this chart. Because the baseline moves, a stream graph is excellent at showing the shape of a changing mix and poor at supporting precise comparisons between two specific values.

Two controls exist to manage exactly that. Inside-out ordering places the largest, steadiest series near the middle and pushes volatile ones to the edges, which is the convention that keeps a streamgraph from looking like noise. Smooth versus straight trades an organic silhouette against being literal about where your data points sit. When precision matters more than shape, switch to stacked area and keep the same palette so the slide still belongs to the same family.

Built for Slides, Not for Dashboards

Every chart is drawn on a fixed 16:9 canvas, so the preview is the slide you get. Palettes are chosen to survive a projector and a grayscale printout, and the monochrome ramp is there for documents that will be photocopied or read by someone who cannot distinguish your brand colours. Transparent backgrounds are available from the start rather than locked behind a paid tier, because a chart that has to sit on your own slide background is the normal case, not a premium one.

With Pro, the Insert into slide export writes a PowerPoint file where each band is a genuine freeform shape rather than a picture. You can select a band, change its fill to your brand colour, nudge it, or restyle the whole chart without ever leaving PowerPoint. That is the difference between a chart you inherited and a chart you own.

Once the chart is built, it still needs a deck around it. SlideModel publishes thousands of editable presentation templates for PowerPoint and Google Slides, so the stream graph you export here can drop into a data-story layout that already matches it — and the rest of the free presentation tools cover the other slides in the same deck.