Four Quick Ways to Launch the Right Python REPL When Multiple Versions Are Installed

When a Windows machine has both Python 2 and Python 3 installed, typing python at the command line launches whichever version appears first in the system PATH. The author demonstrates that on their system Python 2 starts by default because its PATH entry precedes Python 3's. To make Python 3 the default, move its PATH entry above Python 2's.

Method 2 — Open a prompt directly in the installation folder. Navigate to the directory containing python.exe (e.g., the Python 3 install folder). Hold Shift and right-click an empty area, then choose "Open command window here" (or type cmd in the folder's address bar and press Enter). Running python now starts that specific version. The same steps work for Python 2.

Method 3 — Use the py launcher (recommended as fastest). Without any PATH changes, run py -2 to start Python 2 or py -3 to start Python 3. The launcher is installed with Python 3.3+ and automatically detects registered versions.

Method 4 — Virtual environments. The author references two earlier articles on creating default and version-specific virtual environments on Windows. Activating a venv isolates the interpreter and packages, letting you work with a chosen Python version cleanly.

The article concludes that Method 3 ( py -2 / py -3) is the most convenient because it requires no environment-variable edits and works immediately from any directory.