How to Check Python Version

What you’ll build or solve

You’ll identify the exact Python version on your machine and the interpreter path behind it.

When this approach works best

This approach works well when you:

• Installed Python and want to confirm the version you got.
• Set up a project and need to confirm your terminal uses the same Python as your IDE or virtual environment.
• Debug a version-related problem, like a syntax error on code that should work in newer Python.

Skip deep version checks when:

• You run everything inside a container or a managed environment that already pins Python for you.

Prerequisites

• A terminal
  • macOS/Linux: Terminal
  • Windows: PowerShell or Windows Terminal
• No extra tools required. If Python isn’t installed, the first step will make that clear.

Step-by-step instructions

1) Print the Python version from your terminal

Start with the command that most commonly works on your platform.

macOS/Linux:

python3--version

Windows:

py--version

What to look for

If you see “command not found” on macOS/Linux or “not recognized” on Windows, your terminal can’t find Python. Jump to Troubleshooting.

2) Confirm which Python executable your terminal is using

The path shows which install you’re running.

macOS/Linux:

which python3

Windows:

py-c"import sys; print(sys.executable)"

What to look for

If the path points to an unexpected location, your PATH or virtual environment may not be active.

3) Check the version from inside Python

When a tool runs Python for you, ask Python directly. This is especially useful for scripts and CI.

macOS/Linux:

python3-c"import sys; print(sys.version_info)"

Windows:

py-c"import sys; print(sys.version_info)"

What to look for

sys.version_info prints a tuple like (major, minor, micro, ...), which is easy to compare in code.

4) Check the version in a virtual environment

If your project uses a virtual environment, activate it, then check the version again.

macOS/Linux:

source .venv/bin/activate
python--version

Windows (PowerShell):

.\.venv\Scripts\Activate.ps1
python--version

If your venv folder uses a different name, replace .venv with the folder you have.

What to look for

• Your prompt often shows something like (.venv) after activation.
• If the version didn’t change as expected, the venv may not be active or may use a different Python.

Quick tip (Windows): py -0 lists Python versions the launcher knows about. This helps when you have multiple installs.

Examples you can copy

Example 1: Quick check for version and path

macOS/Linux:

python3--version
which python3

Windows:

py--version
py-c"import sys; print(sys.executable)"

Example 2: Guard a script based on Python version

importsys

ifsys.version_info< (3,10):
raiseRuntimeError("This script requires Python 3.10+")

Use this in scripts that rely on newer syntax or standard library features.

Example 3: Confirm a tool is using the Python you expect

Add this to scripts run by your IDE, CI, or automation tools:

importsys

print("Python:",sys.version_info)
print("Executable:",sys.executable)

Run your normal command and compare the printed executable path with what you expect.

Common mistakes and how to fix them

Mistake 1: Checking python --version on macOS/Linux and getting an unexpected result

What you might do

python--version

Why it breaks

Some systems don’t map python to Python 3, and some don’t provide python at all.

Fix

Use python3 for checks:

python3--version
which python3

Mistake 2: Your terminal shows one version, but your IDE runs another

What you might do

Check the version in the terminal, then run the project in your editor and hit version-related errors.

Why it breaks

Your IDE can be configured to use a different interpreter than your terminal.

Fix

Print the interpreter path during the run:

importsys
print(sys.executable)

Then select that same interpreter in your IDE settings, or select your project’s virtual environment interpreter.

Troubleshooting

If you see: python3: command not found (macOS/Linux)

Install Python 3, reopen your terminal, then rerun:

python3--version

If you see (Windows): py is not recognized

Reinstall Python and select the option to add Python to PATH, then rerun:

py--version

If you see: Version changes depending on the terminal app

Different shells can load different PATH configs. Check with:

• macOS/Linux:

which python3

• Windows:

py-c"import sys; print(sys.executable)"

If you see: Your venv activates, but it uses the wrong Python version

Recreate the venv using the Python version you want, then reinstall dependencies.

If you see: Permission errors when running Python from a folder

Move the project to a user-writable directory, then retry.

Quick recap

• Check the version: python3 --version on macOS/Linux or py --version on Windows.
• Check the interpreter path: which python3 or py -c "import sys; print(sys.executable)".
• For scripts and CI, print sys.version_info from inside Python.
• If you use a venv, activate it and run python --version again.
• On Windows, py -0 shows multiple installed Python versions.