How to Install and Use Multiple Python Versions

You can install multiple Python versions side by side, each in its own folder. On Windows, the Python install manager (py install 3.11) adds versions and py -3.11 picks one. On any system, uv or pyenv install and switch them for you.

py install 3.11                     # Windows: Python install manager
py -3.11 script.py                  # run with that version
uv python install 3.11 3.13         # any OS: uv downloads and manages them
pyenv install 3.11                  # macOS / Linux: pyenv

For the screenshots, this machine has Python 3.12 from python.org plus 3.11 and 3.13 installed with uv 0.12.22, all on Windows in a real Command Prompt.

Below you’ll see the same script behaving differently on each version, then how to choose a version per command, per virtual environment and per project folder.

Why install more than one Python version?

Mostly because projects don’t all move at once. A work project might be pinned to 3.11 while you try 3.13 at home, and a library may not support the newest release yet.

Versions really do differ. This script uses itertools.batched(), which arrived in Python 3.12, and runs it on three versions:

import itertools
import sys

v = sys.version_info
print(f"Python {v.major}.{v.minor}.{v.micro}", end="  |  ")

if hasattr(itertools, "batched"):
    print("itertools.batched:", list(itertools.batched("ABCDEF", 2)))
else:
    print("itertools.batched: not available (added in 3.12)")

Command Prompt output:

Python 3.12.5  |  itertools.batched: [('A', 'B'), ('C', 'D'), ('E', 'F')]
Python 3.11.17  |  itertools.batched: not available (added in 3.12)
Python 3.13.16  |  itertools.batched: [('A', 'B'), ('C', 'D'), ('E', 'F')]

The first command uses the Windows py launcher; the other two run each interpreter by its full path. That’s the core idea: each version is a separate program, and you choose which one runs your code.

How to install multiple Python versions on Windows

Since Python 3.14, python.org recommends the Python install manager. Get it from python.org/downloads or the Microsoft Store, and it gives you one py command for installing and choosing versions:

py install 3.11        # install a version
py install 3.13
py list                # see what's installed
py -3.11 script.py     # run with a specific version (py -V:3.11 also works)
py -3.13 -m pip install tabulate   # pip for that version

The older setup, one python.org installer per version, still works and is what this machine uses. Those installers are now deprecated, though, and python.org won’t produce them for Python 3.16 or later.

Either way, py -3.11 runs 3.11. I’d only let one version own the plain python command and reach the others through py -X.Y.

And always install packages with py -X.Y -m pip, or they’ll land in the wrong version. ModuleNotFoundError after pip install is exactly that mix-up.

Create a virtual environment with a specific Python version

A virtual environment remembers the Python that created it. Create it with the version you want, and everything run inside it uses that version:

import itertools
import sys

v = sys.version_info
print(f"Python {v.major}.{v.minor}.{v.micro}", end="  |  ")

if hasattr(itertools, "batched"):
    print("itertools.batched:", list(itertools.batched("ABCDEF", 2)))
else:
    print("itertools.batched: not available (added in 3.12)")

Command Prompt output:

Python 3.11.17  |  itertools.batched: not available (added in 3.12)

With the py command, that’s py -3.11 -m venv env311. This is how I keep old projects on old versions without thinking about it. Virtual environments in Python covers activating and managing them.

Install and switch Python versions with uv

uv is a fast, cross-platform tool that installs Python versions for you, with no installers to click through. It can also pin a version to a project folder, so uv run picks it automatically:

import itertools
import sys

v = sys.version_info
print(f"Python {v.major}.{v.minor}.{v.micro}", end="  |  ")

if hasattr(itertools, "batched"):
    print("itertools.batched:", list(itertools.batched("ABCDEF", 2)))
else:
    print("itertools.batched: not available (added in 3.12)")

Command Prompt output:

cpython-3.13.16-windows-x86_64-none    C:\pyguides\uvpython\cpython-3.13-windows-x86_64-none\python.exe
cpython-3.11.17-windows-x86_64-none    C:\pyguides\uvpython\cpython-3.11-windows-x86_64-none\python.exe
Pinned `.python-version` to `3.11`
Python 3.11.17  |  itertools.batched: not available (added in 3.12)
Updated `.python-version` from `3.11` -> `3.13`
Python 3.13.16  |  itertools.batched: [('A', 'B'), ('C', 'D'), ('E', 'F')]

python -m pip install uv          # or the standalone installer from Astral
uv python install 3.11 3.13       # download and install both
uv python list --only-installed   # see what you have
uv python pin 3.11                # this folder uses 3.11 from now on

Commit the .python-version file and everyone on the project gets the same version. pyenv reads the same file name, which makes the two tools easy to mix on a team.

Multiple Python versions on macOS and Linux

The system Python on macOS and Linux belongs to the operating system, so leave it alone and add your own versions next to it. The common choices are:

Tool	Install a version	Choose one
uv	uv python install 3.11	uv python pin 3.11, uv run
pyenv	pyenv install 3.11	pyenv local 3.11 (writes .python-version)
Homebrew (macOS)	brew install python@3.11	Run python3.11 directly
python.org (macOS)	The installer for each version	python3.11, python3.13

On these systems each version gets a versioned command, so python3.11 -m pip install tabulate is the reliable way to install for one specific version.

How do I check which Python version I’m using?

Run python --version, or print sys.version from inside the script, which tells you what’s actually running your code. Checking your Python version lists every way to do it.

If the version isn’t the one you expected, the usual cause is PATH order: the first python found on PATH wins. Use py -X.Y, a versioned command or an activated virtual environment instead of relying on it.

Multiple Python versions: quick reference

Goal	Windows (py)	uv (any OS)
Install a version	py install 3.11	uv python install 3.11
List installed versions	py list	uv python list --only-installed
Run a script on 3.11	py -3.11 script.py	uv run --python 3.11 script.py
Install a package for 3.11	py -3.11 -m pip install pkg	uv pip install pkg inside a 3.11 venv
Virtual environment on 3.11	py -3.11 -m venv .venv	uv venv --python 3.11
Pin a folder to 3.11	Not built in	uv python pin 3.11

Working through a Python setup? These guides help with the next steps:

• Check your Python version
• Virtual environments in Python
• pip install a specific version of a package
• ModuleNotFoundError after pip install
• Environment variables in Python

Frequently asked questions