How to Use plt.savefig in Matplotlib to Save Plots

Use plt.savefig(filename, dpi=, format=) to save your current matplotlib plot to a file. Specify the file name with extension (like .png or .pdf) and optional parameters like dpi for resolution and format to set the file type explicitly.

Syntax

The basic syntax of plt.savefig is:

• filename: The name of the file where the plot will be saved. Include the file extension like .png, .jpg, or .pdf.
• dpi (optional): Controls the resolution (dots per inch) of the saved image. Higher means sharper image.
• format (optional): Forces the file format if the extension is missing or you want a different format.
• Other optional parameters include bbox_inches to control bounding box and transparent for background transparency.

python

plt.savefig(fname, dpi=None, format=None, bbox_inches=None, transparent=False)

Example

This example creates a simple line plot and saves it as a PNG file with 300 dpi resolution.

python

import matplotlib.pyplot as plt

# Create some data
x = [1, 2, 3, 4, 5]
y = [2, 3, 5, 7, 11]

# Plot the data
plt.plot(x, y, marker='o')
plt.title('Simple Line Plot')
plt.xlabel('X axis')
plt.ylabel('Y axis')

# Save the plot to a file
plt.savefig('line_plot.png', dpi=300)

# Show the plot
plt.show()

Output

A window opens showing the line plot with points connected by lines.

Common Pitfalls

• Calling plt.savefig after plt.show() can save a blank image because plt.show() clears the figure by default.
• Forgetting to include a file extension in filename may cause errors or unexpected formats.
• Not setting bbox_inches='tight' can result in clipped labels or titles in the saved image.

python

import matplotlib.pyplot as plt

plt.plot([1, 2, 3], [4, 5, 6])
plt.savefig('plot_without_extension')  # May cause format issues
plt.show()

# Correct way:
plt.plot([1, 2, 3], [4, 5, 6])
plt.savefig('plot_with_extension.png', bbox_inches='tight')
plt.show()

Quick Reference

Here is a quick summary of common plt.savefig parameters:

Parameter	Description	Example
filename	Name of the file to save the plot (with extension)	'plot.png'
dpi	Resolution of the saved image in dots per inch	dpi=300
format	File format to save (overrides extension)	format='pdf'
bbox_inches	Adjust bounding box to fit content tightly	bbox_inches='tight'
transparent	Make background transparent	transparent=True

Key Takeaways

Always call plt.savefig before plt.show to ensure the plot is saved correctly.

Include a file extension in the filename to specify the image format automatically.

Use dpi parameter to control the image resolution for better quality.

Set bbox_inches='tight' to avoid clipping labels and titles in the saved image.

plt.savefig supports many formats like PNG, JPG, PDF, SVG depending on the filename extension.