How to Check Your Python Version on Windows, macOS, and Linux

Python is a versatile and widely used programming language, powering everything from web applications to data science projects. Knowing which version of Python you have installed is crucial for ensuring compatibility with libraries, frameworks, and code examples. This comprehensive guide will walk you through various methods to check your Python version on Windows, macOS, and Linux operating systems. We’ll cover using the command line, checking within Python scripts, and addressing potential issues like multiple Python installations.

Why is Knowing Your Python Version Important?

Before diving into the how-to, let’s understand why checking your Python version is so important:

* **Compatibility:** Different versions of Python have different features and syntax. Code written for Python 2 might not run correctly on Python 3, and vice versa. Similarly, some libraries and frameworks might only support specific Python versions. Knowing your version allows you to choose compatible libraries and follow tutorials appropriate for your environment.
* **Debugging:** When encountering errors or unexpected behavior in your Python code, the Python version can be a key factor in identifying the root cause. Error messages and stack traces can vary between versions, making it difficult to diagnose the problem without knowing your Python version.
* **Reproducibility:** When sharing your code with others, specifying the Python version used ensures that others can reproduce your results and run your code without compatibility issues.
* **Package Management:** Package managers like `pip` often behave differently depending on the Python version. Knowing your version helps you use `pip` correctly and install the appropriate packages for your environment.
* **Security:** Older versions of Python might have security vulnerabilities that have been addressed in newer versions. Keeping your Python version up to date is essential for maintaining the security of your system.

Checking Python Version on Windows

Windows users have several ways to determine their Python version. We’ll explore the most common methods using the command prompt and PowerShell.

Method 1: Using the Command Prompt (cmd.exe)

The command prompt is a built-in Windows utility for executing commands. Here’s how to check your Python version using it:

1. **Open the Command Prompt:**
* Press the Windows key, type “cmd,” and press Enter. Alternatively, search for “Command Prompt” in the Start menu and click to open it.

2. **Execute the Python Version Command:**
* In the command prompt window, type one of the following commands and press Enter:
* `python –version`
* `python -V` (uppercase V)
* `py –version`
* `py -V` (uppercase V)

3. **Interpret the Output:**
* The command prompt will display the Python version installed on your system. For example:

Python 3.9.7

* If you have multiple Python versions installed, you might need to use `py` to specify the version you want to check. For example, `py -3.9 –version` would check the version of Python 3.9.

**Troubleshooting:**

* **”‘python’ is not recognized as an internal or external command, operable program or batch file.”** This error usually means that Python is not added to your system’s PATH environment variable. To fix this:
1. Search for “environment variables” in the Start menu and click on “Edit the system environment variables.”
2. Click on the “Environment Variables…” button.
3. In the “System variables” section, find the “Path” variable and click “Edit…”.
4. Click “New” and add the path to your Python installation directory (e.g., `C:\Python39`). Also, add the path to the Scripts directory (e.g., `C:\Python39\Scripts`).
5. Click “OK” on all windows and restart your command prompt.

Method 2: Using PowerShell

PowerShell is a more advanced command-line shell and scripting language available on Windows. You can use it to check your Python version in a similar way to the command prompt:

1. **Open PowerShell:**
* Press the Windows key, type “powershell,” and press Enter. Alternatively, search for “PowerShell” in the Start menu and click to open it.

2. **Execute the Python Version Command:**
* In the PowerShell window, type one of the following commands and press Enter:
* `python –version`
* `python -V` (uppercase V)
* `py –version`
* `py -V` (uppercase V)

3. **Interpret the Output:**
* The PowerShell window will display the Python version installed on your system, just like the command prompt.

**Troubleshooting:**

The same troubleshooting steps for the command prompt apply to PowerShell as well. If you encounter the “‘python’ is not recognized” error, ensure that Python is added to your system’s PATH environment variable.

Method 3: Checking Python Version within a Python Script

You can also determine the Python version programmatically using a Python script. This is useful for automatically checking the version in your code or for displaying the version to users.

1. **Create a Python File:**
* Open a text editor (like Notepad, VS Code, or Sublime Text) and create a new file. Save it with a `.py` extension (e.g., `check_version.py`).

2. **Add the Version Checking Code:**
* Paste the following code into the file:

python
import sys

print(sys.version)
print(sys.version_info)

3. **Run the Script:**
* Open your command prompt or PowerShell.
* Navigate to the directory where you saved the `check_version.py` file using the `cd` command (e.g., `cd C:\Users\YourName\Documents`).
* Execute the script using the `python` command:
* `python check_version.py`

4. **Interpret the Output:**
* The script will print two lines of output:
* `sys.version`: This provides a human-readable string containing the Python version information, including the build number and compiler used.
* `sys.version_info`: This returns a named tuple containing the major, minor, micro, releaselevel, and serial version numbers. This is often more useful for programmatic comparisons.

**Example Output:**

3.9.7 (tags/v3.9.7:1dc3e6e, Sep 16 2021, 16:37:26) [MSC v.1929 64 bit (AMD64)]
sys.version_info(major=3, minor=9, micro=7, releaselevel=’final’, serial=0)

**Explanation of `sys.version_info`:**

* `major`: The major version number (e.g., 3).
* `minor`: The minor version number (e.g., 9).
* `micro`: The micro version number (e.g., 7).
* `releaselevel`: Indicates the stability of the release (e.g., ‘final’, ‘alpha’, ‘beta’, ‘candidate’).
* `serial`: The serial number of the release.

This detailed output is beneficial for advanced scripting where you need to perform version-specific actions.

Checking Python Version on macOS

macOS, like Windows, offers several ways to check your Python version. We’ll focus on using the Terminal and Python scripts.

Method 1: Using the Terminal

The Terminal is macOS’s command-line interface. Here’s how to check your Python version using it:

1. **Open the Terminal:**
* You can find the Terminal application in the `/Applications/Utilities/` folder. Alternatively, use Spotlight Search (Command + Space) and type “Terminal”.

2. **Execute the Python Version Command:**
* In the Terminal window, type one of the following commands and press Enter:
* `python3 –version`
* `python3 -V` (uppercase V)
* `python –version`
* `python -V` (uppercase V)

3. **Interpret the Output:**
* The Terminal will display the Python version installed on your system. For example:

Python 3.9.7

**Important Notes for macOS:**

* **Python 2 vs. Python 3:** macOS historically came with Python 2 pre-installed. However, Python 2 is no longer supported. Modern macOS versions typically have Python 3 installed by default. The `python` command might point to Python 2 (if present), so it’s generally recommended to use `python3` to explicitly check the Python 3 version.
* **Multiple Python Installations:** You might have multiple Python versions installed on your Mac, especially if you use tools like Homebrew or Anaconda. The commands listed above will usually show the version that is highest in your PATH.

**Troubleshooting:**

* **”command not found: python3″** This usually means that Python 3 is not installed or not added to your system’s PATH environment variable. You can install Python 3 using Homebrew (a popular package manager for macOS):
1. **Install Homebrew (if you haven’t already):**
bash
/bin/bash -c “$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)”

2. **Install Python 3:**
bash
brew install python3

After installing Python 3 with Homebrew, it should be automatically added to your PATH. Open a new Terminal window to ensure the changes take effect.

Method 2: Checking Python Version within a Python Script (macOS)

The process for checking the Python version within a Python script is identical to the method described for Windows. You can create a `.py` file with the following code:

python
import sys

print(sys.version)
print(sys.version_info)

Save the file (e.g., `check_version.py`), and then run it from the Terminal using the `python3` command (or `python` if that points to your desired Python 3 installation):

bash
python3 check_version.py

This will print the same detailed version information to the Terminal as described in the Windows section.

Checking Python Version on Linux

Linux distributions offer similar methods for checking the Python version as macOS. We’ll focus on using the Terminal and Python scripts.

Method 1: Using the Terminal (Linux)

The Terminal is the primary command-line interface in Linux. Here’s how to check your Python version using it:

1. **Open the Terminal:**
* The method for opening the Terminal varies depending on your Linux distribution. Common methods include searching for “Terminal” in the application menu or using a keyboard shortcut (e.g., Ctrl+Alt+T).

2. **Execute the Python Version Command:**
* In the Terminal window, type one of the following commands and press Enter:
* `python3 –version`
* `python3 -V` (uppercase V)
* `python –version`
* `python -V` (uppercase V)

3. **Interpret the Output:**
* The Terminal will display the Python version installed on your system. For example:

Python 3.8.10

**Important Notes for Linux:**

* **Python 2 vs. Python 3:** Many older Linux distributions came with Python 2 pre-installed. However, Python 2 is no longer supported. Modern Linux distributions typically have Python 3 installed by default. The `python` command might point to Python 2 (if present), so it’s generally recommended to use `python3` to explicitly check the Python 3 version.
* **Package Manager:** Linux distributions use package managers (like `apt`, `yum`, `dnf`, etc.) to install and manage software. If Python 3 is not installed, you can use your distribution’s package manager to install it. For example, on Debian-based systems (like Ubuntu), you can use `apt`:

bash
sudo apt update
sudo apt install python3

**Troubleshooting:**

* **”command not found: python3″** This usually means that Python 3 is not installed. Use your distribution’s package manager to install it (as shown above).

Method 2: Checking Python Version within a Python Script (Linux)

The process for checking the Python version within a Python script is identical to the methods described for Windows and macOS. You can create a `.py` file with the following code:

python
import sys

print(sys.version)
print(sys.version_info)

Save the file (e.g., `check_version.py`), and then run it from the Terminal using the `python3` command (or `python` if that points to your desired Python 3 installation):

bash
python3 check_version.py

This will print the same detailed version information to the Terminal as described in the Windows section.

Dealing with Multiple Python Installations

It’s not uncommon to have multiple Python versions installed on your system, especially if you’re a developer working on different projects or using tools like Anaconda. Here’s how to manage multiple Python installations:

* **Using `py` (Windows):** On Windows, the `py` command is a Python launcher that helps you specify which Python version to use. You can use `py -3.x` (e.g., `py -3.9`) to run a specific Python 3 version. Use `py –list` to see a list of installed versions.
* **Using Virtual Environments:** Virtual environments are isolated Python environments that allow you to install packages specific to a project without affecting other projects or the system-wide Python installation. This is the recommended way to manage dependencies and avoid conflicts between different Python versions. Tools like `venv` (built into Python) and `virtualenv` can be used to create virtual environments.

**Example using `venv`:**

1. **Create a virtual environment:**
bash
python3 -m venv myenv

2. **Activate the virtual environment:**
* **Windows:** `myenv\Scripts\activate`
* **macOS/Linux:** `source myenv/bin/activate`
3. **Install packages:** Use `pip` to install packages within the virtual environment.
4. **Deactivate the virtual environment:** `deactivate`

* **Using Anaconda (if installed):** Anaconda is a popular Python distribution that includes a package manager called `conda`. `conda` allows you to create and manage multiple environments, each with its own Python version and packages. You can use the `conda create` command to create a new environment with a specific Python version:

bash
conda create -n myenv python=3.9
conda activate myenv

Conclusion

Knowing your Python version is a fundamental skill for any Python developer. This guide has provided you with detailed instructions on how to check your Python version on Windows, macOS, and Linux using various methods. Whether you prefer using the command line, PowerShell, Terminal, or checking within a Python script, you now have the tools to confidently determine your Python version and ensure compatibility in your projects. Remember to manage multiple Python installations effectively using tools like virtual environments or Anaconda to avoid conflicts and maintain project isolation. Regularly checking your Python version and keeping it up to date is crucial for taking advantage of new features, bug fixes, and security improvements.