How to Install a Module in Python (pip Guide)

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Here’s how to install a module in Python: run python -m pip install followed by the package name, ideally inside a virtual environment. Then import it in your code:

python -m pip install humanize      # Windows: py -m pip install humanize
python3 -m pip install humanize     # macOS / Linux

I ran every command below in a fresh virtual environment with Python 3.12.5 on Windows, so the output is exactly what pip printed.

We’ll go from a ModuleNotFoundError to a working import, then check, upgrade, pin and remove modules, and sort out the package-name versus import-name trap.

How to install a module in Python with pip

Here’s the usual sequence: the script fails because the module isn’t installed, you install it with pip, and the same script works:

import humanize

print(humanize.intcomma(1250500))
print(humanize.naturalsize(52_428_800))
print(humanize.ordinal(3), "place")

Output:

Traceback (most recent call last):
  File "C:\pyguides\use_humanize.py", line 1, in <module>
    import humanize
ModuleNotFoundError: No module named 'humanize'
Collecting humanize
  Using cached humanize-4.16.0-py3-none-any.whl.metadata (8.0 kB)
Using cached humanize-4.16.0-py3-none-any.whl (137 kB)
Installing collected packages: humanize
Successfully installed humanize-4.16.0
1,250,500
52.4 MB
3rd place
Command Prompt showing a Python ModuleNotFoundError for humanize, then python -m pip install humanize, then the script running successfully
Before the install: ModuleNotFoundError. After: the script prints formatted numbers.

python -m pip runs pip for that exact Python, so the module lands where your script will look. Plain pip can belong to a different Python on your PATH, which is the most common reason an install “didn’t work”.

If you still see the error after installing, ModuleNotFoundError after pip install walks through every cause.

Why install modules in a virtual environment?

A virtual environment is a private folder of packages for one project, so projects can’t break each other with different versions. Creating one is a single command:

python -m venv .venv
.venv\Scripts\activate            # Windows
source .venv/bin/activate         # macOS / Linux
python -m pip install humanize

On recent Ubuntu, Debian and Homebrew Python, pip refuses to install into the system Python at all, so a venv isn’t optional there. See Python virtual environments.

Checking, pinning and upgrading installed modules

pip show describes one package, pip list shows everything installed, and you can install an exact version or upgrade to the latest:

.modenv\Scripts\python -m pip --disable-pip-version-check show humanize
.modenv\Scripts\python -m pip --disable-pip-version-check list
.modenv\Scripts\python -m pip --disable-pip-version-check install humanize==4.9.0
.modenv\Scripts\python -m pip --disable-pip-version-check install --upgrade humanize

Output:

Name: humanize
Version: 4.16.0
Summary: Python humanize utilities
Home-page: https://github.com/python-humanize/humanize
Author: 
Author-email: Jason Moiron <jmoiron@jmoiron.net>
License: 
Location: C:\pyguides\.modenv\Lib\site-packages
Requires: 
Required-by:
Package  Version
-------- -------
humanize 4.16.0
pip      24.2
Collecting humanize==4.9.0
  Using cached humanize-4.9.0-py3-none-any.whl.metadata (7.9 kB)
Using cached humanize-4.9.0-py3-none-any.whl (126 kB)
Installing collected packages: humanize
  Attempting uninstall: humanize
    Found existing installation: humanize 4.16.0
    Uninstalling humanize-4.16.0:
      Successfully uninstalled humanize-4.16.0
Successfully installed humanize-4.9.0
Requirement already satisfied: humanize in c:\pyguides\.modenv\lib\site-packages (4.9.0)
Collecting humanize
  Using cached humanize-4.16.0-py3-none-any.whl.metadata (8.0 kB)
Using cached humanize-4.16.0-py3-none-any.whl (137 kB)
Installing collected packages: humanize
  Attempting uninstall: humanize
    Found existing installation: humanize 4.9.0
    Uninstalling humanize-4.9.0:
      Successfully uninstalled humanize-4.9.0
Successfully installed humanize-4.16.0
Command Prompt output of pip show and pip list for an installed Python module, installing version 4.9.0, then upgrading it
pip replaced the newer version with 4.9.0 when asked, then upgraded back to the latest.

For reproducible projects, list your modules in a file and install them together; see pip install -r requirements.txt and pip install a specific version.

Why does pip install fail for some module names?

The name you import isn’t always the name you install. Pillow is imported as PIL, but pip install PIL fails because no such package exists:

from PIL import Image                      # installed as "Pillow", imported as "PIL"

img = Image.new("RGB", (120, 60), "navy")
print("Pillow works, image size:", img.size)

Output:

ERROR: Could not find a version that satisfies the requirement PIL (from versions: none)
ERROR: No matching distribution found for PIL
Collecting Pillow
  Using cached pillow-12.3.0-cp312-cp312-win_amd64.whl.metadata (9.3 kB)
Using cached pillow-12.3.0-cp312-cp312-win_amd64.whl (7.2 MB)
Installing collected packages: Pillow
Successfully installed Pillow-12.3.0
Pillow works, image size: (120, 60)
Command Prompt output of pip failing to install PIL, then installing Pillow and importing PIL successfully
Install “Pillow”, import “PIL”. The error tells you there’s no PIL package on PyPI.
You importYou install
PILPillow
bs4beautifulsoup4
cv2opencv-python
sklearnscikit-learn
yamlPyYAML
dotenvpython-dotenv

When in doubt, search the module on pypi.org; the install command is at the top of each project page.

Uninstalling a module

pip uninstall removes a package; -y skips the confirmation prompt. Importing it afterward fails again, which confirms it’s gone:

.modenv\Scripts\python -m pip --disable-pip-version-check uninstall -y humanize
.modenv\Scripts\python -c "import humanize"

Output:

Found existing installation: humanize 4.16.0
Uninstalling humanize-4.16.0:
  Successfully uninstalled humanize-4.16.0
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'humanize'
Command Prompt output of pip uninstall removing a Python module and the import failing with ModuleNotFoundError
Uninstalled, then the import fails, as expected.

uv, a newer tool, does the same jobs much faster with uv pip install and uv add. Many of my projects use it now; the commands map almost one to one.

pip commands cheat sheet

TaskCommand
Installpython -m pip install requests
Install a versionpython -m pip install requests==2.32.3
Upgradepython -m pip install --upgrade requests
Uninstallpython -m pip uninstall requests
Show detailspython -m pip show requests
List installedpython -m pip list
Check conflictspython -m pip check

Related setup guides you may need:

Frequently asked questions

How do I install a module in Python?

Run python -m pip install module-name in a terminal, preferably inside an activated virtual environment, then import it in your code.

Why do I still get ModuleNotFoundError after pip install?

pip installed it into a different Python. Use python -m pip install with the same python that runs your script.

What’s the difference between pip and python -m pip?

python -m pip guarantees pip runs for that interpreter. Plain pip may point at another Python on your PATH.

How do I install a module in VS Code?

Select your interpreter or venv in VS Code, open its terminal, and run python -m pip install module-name there.

Can I install modules without internet?

Yes, from downloaded wheel files: python -m pip install path/to/package.whl.

Where is the official guide?

See Installing Python Modules in the Python docs.