Matplotlib Pie Charts

What a Pie Chart Is For

A pie chart shows how a total is split into parts, such as market share by company or a budget split across expense categories. It works best with a small number of slices — beyond five or six categories, the slices become hard to compare by eye, and a bar chart usually communicates the same information more clearly.

Basic Pie Chart

plt.pie(values) draws one slice per value, sized proportionally to that value's share of the total. Pass labels to name each slice.

import matplotlib.pyplot as plt

browsers = ["Chrome", "Safari", "Edge", "Firefox", "Other"]
market_share = [63, 19, 8, 6, 4]

plt.pie(market_share, labels=browsers)
plt.title("Browser market share")
plt.show()

Showing Percentages with autopct

The autopct argument prints a value directly on each slice, computed from that slice's share of the total. It takes a printf-style format string: "%1.1f%%" prints the percentage with one digit after the decimal point, followed by a literal percent sign.

import matplotlib.pyplot as plt

expenses = ["Housing", "Food", "Transport", "Entertainment"]
monthly_spend = [1200, 450, 300, 150]

plt.pie(monthly_spend, labels=expenses, autopct="%1.1f%%", startangle=90)
plt.title("Monthly expense breakdown")
plt.show()

The explode argument accepts a list matching the number of slices, where each number is how far that slice should be pushed out from the center — 0 keeps a slice in place. Combine this with plt.legend() when slice labels are too crowded to print directly next to small slices.

import matplotlib.pyplot as plt

teams = ["Team A", "Team B", "Team C", "Team D"]
points_scored = [28, 35, 19, 42]
explode = [0, 0, 0, 0.1]
colors = ["#4C72B0", "#DD8452", "#55A868", "#C44E52"]

plt.pie(points_scored, labels=teams, explode=explode, colors=colors,
        autopct="%1.0f%%", shadow=True)
plt.legend(title="Teams")
plt.show()

• labels names each slice; without it, slices are drawn with no text at all.
• autopct formats and prints a value on each slice, most often a percentage.
• explode shifts one or more slices outward to draw attention to them.
• colors sets an explicit color per slice, overriding Matplotlib's default color cycle.
• startangle rotates the whole chart so the first slice does not have to start at the 3 o'clock position.