Chart.js Polar Area Chart — Segmented Circular Display
In this tutorial, you will learn about Chart.js Polar Area Chart. We cover key concepts, practical examples, and best practices to help you master this topic.
Chart.js polar area charts display data as segments in a circular layout where each segment's arc length and radius represent the value proportionally.
What You'll Learn
By the end of this guide, you will create polar area charts with custom colors, configure Angular and radial axes, animate segments, and build an expense breakdown visualization.
Basic Polar Area Chart
new Chart(document.getElementById('polar'), {
type: 'polarArea',
data: {
labels: ['Rent', 'Food', 'Transport', 'Entertainment', 'Savings'],
datasets: [{
data: [1200, 600, 300, 400, 500],
backgroundColor: [
'#ff6b35', '#4ecdc4', '#2a9d8f',
'#e8a87c', '#95e1d3'
]
}]
},
options: {
responsive: true,
scales: {
r: {
beginAtZero: true
}
}
}
});
Custom Segment Styling
datasets: [{
data: [1200, 600, 300, 400, 500],
backgroundColor: ['#ff6b35', '#4ecdc4', '#2a9d8f', '#e8a87c', '#95e1d3'],
borderColor: '#fff',
borderWidth: 2,
hoverBackgroundColor: ['#e85a2a', '#3dbdb5', '#258c7e', '#d3986c', '#85d1c3']
}]
Common Mistakes
1. Too Many Segments
Polar area charts with more than 8 segments become visually confusing. Combine small items into "Other."
2. Not Sorting by Value
Unsorted segments make comparison harder. Sort data descending before rendering.
3. Inconsistent Segment Sizes
Small values are hard to see. Consider a threshold for minimum display size.
4. Missing Hover Effects
Hover effects improve UX. Use hoverBackgroundColor and hoverBorderColor.
5. Using on Small Screens
Polar area charts need space. Use a minimum canvas size of 300x300.
Practice Questions
Q1: What is the difference between polarArea and pie? A: In polarArea, both arc length and radius vary with value. In pie, only arc length varies.
Q2: How many segments are recommended? A: 5-8 segments maximum. Group smaller categories.
Q3: How do you animate the chart? A: Animation is enabled by default. Configure animation.duration and animation.animateRotate.
Q4: What scale type is used?
A: The radial scale scales.r with beginAtZero.
Q5: Can you combine polarArea with other types? A: No. PolarArea is standalone. But multiple polarArea charts can share a page.
Challenge: Build a monthly budget breakdown with 6 categories. Add a legend showing percentage of total.
FAQ
Try It Yourself
Build an expense breakdown polar area chart.
<!DOCTYPE html>
<html>
<head>
<title>Polar Area Demo</title>
<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>
</head>
<body style="font-family:sans-serif;padding:20px;">
<h2>Monthly Expenses</h2>
<canvas id="polar" width="400" height="400"></canvas>
<script>
new Chart(document.getElementById('polar'), {
type: 'polarArea',
data: {
labels: ['Rent', 'Food', 'Transport', 'Entertainment', 'Savings', 'Utilities'],
datasets: [{
data: [1200, 600, 300, 400, 500, 250],
backgroundColor: [
'#ff6b35', '#4ecdc4', '#2a9d8f',
'#e8a87c', '#95e1d3', '#f7dc6f'
],
borderColor: '#fff',
borderWidth: 2
}]
},
options: {
responsive: true,
plugins: {
tooltip: {
callbacks: {
label: function(ctx) {
var total = ctx.dataset.data.reduce(function(a, b) { return a + b; });
var pct = Math.round(ctx.parsed.r / total * 100);
return '$' + ctx.parsed.r + ' (' + pct + '%)';
}
}
}
},
scales: {
r: {
beginAtZero: true,
ticks: { stepSize: 200 }
}
}
}
});
</script>
</body>
</html>
What's Next
Combine multiple chart types in one chart.
Mixed Charts — Combining chart types. Scale Options — Advanced scale configuration.
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