How to Add Value Labels on Bar Chart in Matplotlib

To add value labels on a bar chart in matplotlib, use a loop over the bars and call ax.text() to place the label above each bar. This method lets you display the height or value of each bar clearly on the chart.

Syntax

Use ax.text(x, y, label) inside a loop over bars to add labels. Here:

• ax is the axes object.
• x is the horizontal position of the label (usually the bar center).
• y is the vertical position (usually the bar height).
• label is the text to display (e.g., the bar height).

python

for bar in bars:
    height = bar.get_height()
    ax.text(bar.get_x() + bar.get_width() / 2, height, f'{height}', ha='center', va='bottom')

Example

This example creates a simple bar chart and adds value labels on top of each bar showing their heights.

python

import matplotlib.pyplot as plt

values = [5, 7, 3, 8]
categories = ['A', 'B', 'C', 'D']

fig, ax = plt.subplots()
bars = ax.bar(categories, values)

for bar in bars:
    height = bar.get_height()
    ax.text(bar.get_x() + bar.get_width() / 2, height, f'{height}', ha='center', va='bottom')

plt.show()

Output

A bar chart with four bars labeled 5, 7, 3, and 8 above each bar respectively.

Common Pitfalls

Common mistakes include placing labels inside the bars where they are hard to read or forgetting to center the text horizontally. Also, not adjusting the vertical position can cause labels to overlap the bars or be cut off.

Always use ha='center' to center labels horizontally and va='bottom' to place them just above the bar.

python

import matplotlib.pyplot as plt

values = [4, 6, 2]
categories = ['X', 'Y', 'Z']

fig, ax = plt.subplots()
bars = ax.bar(categories, values)

# Wrong: labels inside bars, not centered
for bar in bars:
    height = bar.get_height()
    ax.text(bar.get_x() + bar.get_width() / 2, height / 2, f'{height}')  # Not centered, inside bar

plt.show()

Output

A bar chart with labels placed at the center inside each bar, making them hard to read.

Quick Reference

• Use ax.text() to add labels.
• Calculate label x-position as bar.get_x() + bar.get_width() / 2.
• Set vertical position to bar height.
• Use ha='center' and va='bottom' for good label placement.

Key Takeaways

Use a loop over bars and ax.text() to add value labels on bar charts.

Center labels horizontally with ha='center' and place them just above bars with va='bottom'.

Calculate label positions using bar x-position plus half the bar width and the bar height.

Avoid placing labels inside bars without centering as it reduces readability.

Adding value labels helps make bar charts easier to understand at a glance.