Area-encoded values
Each sector's area scales with its value, making magnitude differences immediately visible at a glance.
Nightingale Chart
Free Online Nightingale Chart Maker
What is a Nightingale Chart?
A Nightingale chart — also called a polar area chart or rose diagram — displays categorical data as wedge-shaped sectors radiating from a center point, where each sector's area represents its value. Made famous by Florence Nightingale's 1858 mortality analysis, it excels at comparing multiple categories in a visually striking circular layout. Use it when you want to show proportions across cyclical or grouped categories with more visual impact than a standard bar chart.
Key Features
Multi-segment support
Add up to a dozen labeled segments — ideal for disease categories, monthly data, or survey responses.
Adjustable inner radius
Set an inner radius to create a donut-style rose chart, giving the center space for a title or summary value.
Custom colors per segment
Assign distinct colors to each category so readers can distinguish groups without relying on labels alone.
Flexible label modes
Show label only, value only, percent, or combinations — choose the detail level that serves your audience.
Legend positioning
Place the legend at the top, right, bottom, or left to fit your layout without cluttering the chart.
Best For
Comparing causes of mortality or medical outcomes across categories
Visualizing cyclical data such as monthly sales or seasonal trends
Presenting survey results across multiple response categories
Showing budget or resource allocation across departments
Displaying frequency distributions where category order carries meaning
Academic and research presentations requiring historical chart styles
When to Use
- When you have 4–12 categorical groups each with a single numeric value
- When you want more visual impact than a bar chart for the same comparison
- When category order has meaning, such as months, directions, or ranked groups
- When presenting data that was historically displayed this way, such as epidemiology or mortality reports
- When your audience is comfortable with circular charts and you want visual variety
Common Mistakes
- Using too many segments — more than 12 sectors cause labels to overlap and comparisons become unreadable
- Confusing area with radius — viewers often misjudge sector size by comparing radii instead of areas
- Skipping a legend when color is the only way to identify segments
- Choosing this chart when values are very similar — small differences are hard to read in polar form
- Omitting units or a clear title, leaving readers unsure what the values represent
- Picking a Nightingale chart when a simple bar chart would communicate the comparison more clearly
Templates
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