How to Install Updated Python 3.6.x on Mac

Jun 13, 2018 - 4 Comments

Install Python 3 on Mac

Python is a popular programming language that is widely used by beginners and longtime developers alike. Modern Mac OS versions come with Python 2.7.x installed (or Python 2.6.1 if an older Mac OS X version), but many Python users may need to update Python in Mac OS to a newer version like Python 3.6.5.

This article will discuss how to get an updated Python 3 installation on the Mac by covering two different ways to quickly and easily install Python 3 onto a Mac.


Note that we said install Python 3, not update to Python 3, because how this will work is installing Python 3 while simultaneously maintaining Python 2 on the Mac. This is essential because apparently some Mac apps rely on Python 2 support, so if you attempt to upgrade Python 2.x to Python 3.x in Mac OS you will eventually find that something is broken, perhaps critically so. With that in mind you should not attempt to update the existing preinstalled Python release on a Mac, instead you will just have a co-installation of Python 3 for full compatibility.

And yes, Python 3 and Python 2 can coexist on a Mac without any conflict, the usage commands will just be slightly different.

How to Install the Updated Python 3 in Mac OS

Perhaps the simplest way to install Python 3 is by using the Python package installer from python.org

  1. Go to Python.org downloads page here and download the latest Python installer package
  2. Run the Python installer package and install Python 3 onto the Mac
  3. Installing Python 3 on Mac OS

Python 3.6.x requires about 100mb of disk space to install. Installation is quick, and you’ll have Python 3.x alongside Python 2.x on the Mac.

Once Python 3 is installed you will find a Python3 folder within the /Applications directory of your Mac. You’ll also find the simple IDE called IDLE within the /Applications/MacPython3/ directory, which basically gives you the same Python IDE you’d encounter if you ran ‘python3’ at the command prompt in Terminal.

You can also install Python 3.x on a Mac through Homebrew, which is my preferred method as a Homebrew user.

How to Install Python 3.6.5 with Homebrew

Installing an updated version of Python 3.6.5 (as of time of writing) is super easy with HomeBrew. Of course you will need Homebrew installed on the Mac before you can use the Homebrew method, but if you’re interested in messing around with Python then Homebrew will probably appeal to you anyway.

We’re going to assume you already have Homebrew, if you don’t the you can read here how to install Homebrew on Mac OS.

To install the latest version of Python 3 using Homebrew, just issue the following command string:

brew install python3

Once the updated Python 3 has been installed on the Mac, you can run it with:

python3

Whether you install the updated Python 3 with the package installer or Homebrew, the default version of Python 2.7 that comes preinstalled with Mac OS and Mac OS X will still be installed, completely untouched, and can be run with the simple “python” command as always.

How to Check What Version of Python is Currently Installed in Mac OS

From the Terminal application, simply typing the following command will report back what version of Python is currently installed:

python --version

In MacOS, you will find it’s typically Python 2.7.x of some variation, either 2.7.4 or 2.7.10 or similar.

After you have installed Python with Homebrew or with the package installer, you can check the updated new version of Python with:

python3 --version

And as mentioned before, both installations of Python will coexist without conflict.

Check python versions installed on Mac

You can also find out where each version of python is installed with the ‘which’ or ‘whereis’ command:

Which python installed where on Mac

Note that some aspects of Python are different in each version, and even features like the instant Python simple web server trick is different from version 2 to version 3. If you’re planning on using something longterm, or learning in general, you’ll be better off writing in Python 3.x rather than the older Python 2.x releases.

So now that you’ve got Python 3 installed, you’re ready to roll!

Learning Python, and Python Resources

If you’re new to Python and programming in general, there are a variety of great resources out there to get you started.

If you’re the type to enjoy learning from a book, some popular choices are:

You can check out free online courses too, including these from MIT:

Or you can also explore the broad Python Wiki resources page here too.

TLDR: Don’t Update Python 2.x to Python 3.x, Just Install Python 3.x on the Mac

TLDR: Don’t update the preinstalled Python 2.x to Python 3.x, it will likely break something in doing so. Instead, just install and run the updated Python 3 separately.

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Posted by: Paul Horowitz in Command Line, Mac OS X, Tips & Tricks

4 Comments

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  1. Elwood Downey says:

    my brew seems to want to only upgrade:

    ecd-imac27: brew install python3
    Error: python 2.7.14_2 is already installed
    To upgrade to 3.6.5, run `brew upgrade python`

    • Paul says:

      Curious, what version of macOS?

      If you updated system software recently, may try:

      brew doctor

      And then try installing again.

      Also might be interesting to see specifics about what it thinks came from Homebrew:

      brew info python

      and

      brew info python3

  2. Tomatos says:

    peenv is very useful tool. I recommend use it to switch between many python versions in system.

  3. macpytho says:

    Fitting, I needed Python 3.6 for the Gif to ASCII CLI tool and it works great.

    https://github.com/google/gif-for-cli

    Cheers, thanks for helping upgrade to Python 3.6!

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