Locust is available on PyPI and can be installed with pip.

$ pip3 install locust

If you want the bleeding edge version, you can use pip to install directly from our Git repository. For example, to install the master branch using Python 3:

$ pip3 install -e git://

Once Locust is installed, a locust command should be available in your shell. (if you’re not using virtualenv—which you should—make sure your python script directory is on your path).

To see available options, run:

$ locust --help

Supported Python Versions

Locust is supported on Python 3.6, 3.7 and 3.8.

Installing Locust on Windows

On Windows, running pip install locustio should work.

However, if it doesn’t, chances are that it can be fixed by first installing the pre built binary packages for pyzmq, gevent and greenlet.

You can find an unofficial collection of pre built python packages for windows here:

When you’ve downloaded a pre-built .whl file, you can install it with:

$ pip install name-of-file.whl

Once you’ve done that you should be able to just pip install locustio.


Running Locust on Windows should work fine for developing and testing your load testing scripts. However, when running large scale tests, it’s recommended that you do that on Linux machines, since gevent’s performance under Windows is poor.

Installing Locust on macOS

The following is currently the shortest path to installing gevent on OS X using Homebrew.

  1. Install Homebrew.
  2. Install libev (dependency for gevent):
brew install libev
  1. Then follow the above instructions.

Increasing Maximum Number of Open Files Limit

Every HTTP connection on a machine opens a new file (technically a file descriptor). Operating systems may set a low limit for the maximum number of files that can be open. If the limit is less than the number of simulated users in a test, failures will occur.

Increase the operating system’s default maximum number of files limit to a number higher than the number of simulated users you’ll want to run. How to do this depends on the operating system in use.