Using Matplotlib, changing the size of the figure is quite straightforward.

While declaring the figure and the axes, you can define your figure size using the figsize parameter and pass by a tuple with the width and the length in inches. (e.g. (12,6))

Here is an example

# For our example dataframe
import pandas as pd
# For our plot
import matplotlib.pyplot as plt

# Generating sample data
df = pd.DataFrame({"col1":range(10)})

# Creating a figure and the axes for our plots
# We set the figsize to 12 inches wide and 6 inches tall 
fig, axes = plt.subplots(1,1, figsize=(12,6)) 

# We plot
axes.plot(df["col1"])

# We make our canvas tidy and clean
plt.tight_layout()

# We show the graph
plt.show()

Here you are! You now know how to change the size of a figure with Matplotlib

More on plots

If you want to know more about how to add labels, plot different types of plots, etc... check out the other articles I wrote on the topic, just here :

Matplotlib - The Python You Need

We gathered the only Python essentials that you will probably ever need.

The Python You Need