Combo Chart
Also called: Line and column chart, Dual-axis chart, Bar-line chart
A combo chart combines columns and a line in one visual, usually on two y-axes, to compare a volume (like revenue) with a rate (like margin) over the same time period.
When to use a combo chart
Use a combo when two measures share a time axis but have different units or scales, and the relationship between them is the point:
- Revenue ($) and margin (%)
- Orders (count) and average order value ($)
- Headcount and attrition rate
- Sessions and conversion rate
Columns usually show the volume and the line shows the rate.
Best practices
- Colour-match each axis to its series so readers know which scale to read.
- Keep it to one line and one column series. More than that and the chart gets hard to read.
- Put a legend at the top, with a clear name and unit for each series.
Mocking up a combo chart
Stakeholders often ask for “revenue and margin on one chart”. Mock it up with realistic numbers first. Sometimes two small charts stacked on top of each other read more clearly, and it’s much easier to find that out on a mockup.
