The Good, the Bad, and the Ugly of Combo Charts

When one chart tries to do everything

Opening: The Familiar Confusion

Have you ever sat in a meeting, looked at a chart, and thought:

“This looks impressive.” “This must be important.” “…I have no idea what it’s telling me.”

Chances are, that was a combo chart.

Bars and lines. Two axes. Multiple measures fighting for attention.

A combo chart is a visualization that combines two chart types (commonly bars and lines) to show magnitude alongside trend or rate.

Combo charts are everywhere—dashboards, management decks, performance reviews. They promise efficiency: one chart, many insights.

Sometimes, they deliver. Often, they don’t.

Let’s talk about the good, the bad, and the ugly of combo charts—and why clarity, not complexity, should always win.

The Good: When Combo Charts Earn Their Place

Combo charts are not villains. They’re power tools—and power tools exist for a reason.

1. When showing scale and performance together matters

Consider a monthly sales review.

You show:

• Revenue as bars

• Profit margin as a line

Suddenly, the conversation shifts.

Instead of:

“Sales are up. Good job.”

It becomes:

“Sales are up—but margins are slipping. Why?”

That’s a real insight. Two related measures. One shared timeline. One clear question.

In this case, the combo chart reduces cognitive load instead of increasing it.

2. When different units must be compared over time

Some measures will never share the same unit:

• Dollars vs percentages

• Volumes vs rates

• Costs vs defect ratios

Separating them into two charts may technically be “cleaner,” but it can hide relationships.

A well-designed combo chart allows viewers to track:

• Direction

• Pattern

• Alignment (or misalignment)

The key word here is well-designed.

3. When executives want one story, not five charts

At senior levels, attention is scarce.

A combo chart—used intentionally—can:

• Reduce slide clutter

• Anchor discussion

• Act as a visual summary

• 
  

The chart doesn’t replace explanation. It supports it.

That’s the good.

The Bad: Where Combo Charts Start to Hurt Communication

This is where things quietly go wrong.

1. Dual axes without mental scaffolding

Two vertical axes are not intuitive.

When viewers see:

• Bars on the left

• A line on the right

• Two scales

• One legend

They pause.

Not because they’re thinking deeply—but because they’re trying to decode.

If a chart requires verbal translation before it makes sense, the chart has already failed as a communication tool.

2. Too many messages in one visual

Combo charts are often used as a dumping ground:

• Targets

• Actuals

• Trends

• Benchmarks

• Forecasts

All in one view.

What happens next is predictable:

• The eye doesn’t know where to land

• The audience picks the wrong takeaway

• Or worse—everyone takes away something different

• 
  

That’s not insight.That’s ambiguity dressed up as sophistication.

3. Poor visual hierarchy

In many combo charts:

• The less important measure is visually louder

• Colors compete

• Lines dominate bars unintentionally

• 
  

The chart technically contains the right data—but visually tells the wrong story.

In meetings, this often shows up as:

“Let’s talk about this line…”“…actually, no—ignore that.”

If your chart needs to be verbally corrected, it’s not helping you.

The Ugly: When Combo Charts Become Dangerous

This is where combo charts stop being confusing—and start being misleading.

1. Axis manipulation to exaggerate meaning

Stretch one axis. Compress the other.

Suddenly:

• A small change looks dramatic

• Flat performance looks volatile

• Weak results look impressive

• 
  

Sometimes this is intentional.Often, it’s accidental.

Either way, the outcome is the same:decisions are made based on distorted perception.

2. Combo charts used to avoid prioritisation

Some combo charts exist because no one wants to decide:

• What matters most

• What can be removed

• What the audience actually needs

So everything stays.

This isn’t storytelling. It’s fear of omission.

Good communication requires courage—the courage to leave things out.

3. Using combo charts for exploration instead of explanation

Combo charts are presentation tools, not thinking tools.

If you’re still asking:

• “Is this trend real?”

• “Which metric matters more?”

• “What’s driving this change?”

• 
  

You’re not ready to combine anything.

Explore first. Explain later.

A Simple Decision Framework

Before using a combo chart, ask yourself:

1. What single question does this chart answer?

2. Do the measures have a meaningful relationship—or just convenience?

3. Can I explain this chart in one sentence?

4. Would two simpler charts reduce confusion?

   
   

If the answer isn’t clear, the chart isn’t ready.

Closing Reflection

Combo charts aren’t bad. But they amplify both clarity and confusion.

Used well, they sharpen decisions. Used poorly, they blur responsibility. Used carelessly, they mislead quietly.

And in data communication, quiet confusion is the most dangerous kind.