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fastai makes deep learning with PyTorch faster, more accurate, and easier

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The fastai library simplifies training fast and accurate neural nets using modern best practices. See the fastai website to get started. The library is based on research into deep learning best practices undertaken at, and includes "out of the box" support for vision, text, tabular, and collab (collaborative filtering) models. For brief examples, see the examples folder; detailed examples are provided in the full documentation. For instance, here's how to train an MNIST model using resnet18 (from the vision example):

data = image_data_from_folder(MNIST_PATH)
learn = create_cnn(data, tvm.resnet18, metrics=accuracy)

Note for students

If you are using fastai for any course, you need to use fastai 0.7.x. Please ignore the rest of this document, which is written for fastai 1.0.x, and instead follow the installation instructions here.

Note: If you want to learn how to use fastai v1 from its lead developer, Jeremy Howard, he will be teaching it in the Deep Learning Part I course at the University of San Francisco from Oct 22nd, 2018.


fastai-1.x can be installed with either conda or pip package managers and also from source. At the moment you can't just run install, since you first need to get the correct pytorch version installed - thus to get fastai-1.x installed choose one of the installation recipes below using your favourite python package manager.

If your system has a recent NVIDIA card with the correctly configured NVIDIA driver please follow the GPU installation instructions. Otherwise, the CPU-ones.

It's highly recommended you install fastai and its dependencies in a virtual environment (conda or others), so that you don't interfere with system-wide python packages. It's not that you must, but if you experience problems with any dependency packages, please consider using a fresh virtual environment just for fastai.

If you experience installation problems, please read about installation issues.

Conda Install

  • GPU

    conda install -c pytorch pytorch-nightly cuda92
    conda install -c fastai torchvision-nightly
    conda install -c fastai fastai
  • CPU

    conda install -c pytorch pytorch-nightly-cpu
    conda install -c fastai torchvision-nightly-cpu
    conda install -c fastai fastai

Note that JPEG decoding can be a bottleneck, particularly if you have a fast CPU. You can optionally install an optimized JPEG decoder as follows (Linux):

conda uninstall --force jpeg libtiff -y
conda install -c conda-forge libjpeg-turbo
CC="cc -mavx2" pip install --no-cache-dir -U --force-reinstall pillow-simd

PyPI Install

  • GPU

    pip install torch_nightly -f
    pip install fastai
  • CPU

    pip install torch_nightly -f
    pip install fastai

NB: this set will also fetch torchvision-nightly, which supports torch-1.x.

Developer Install

First, follow the instructions above for either PyPi or Conda. Then uninstall the fastai package using the same package manager you used to install it, i.e. pip uninstall fastai or conda uninstall fastai, and then, replace it with a pip editable install.

git clone
cd fastai
pip install -e .[dev]

You can test that the build works by starting the jupyter notebook:

jupyter notebook

and executing an example notebook. For example load examples/tabular.ipynb and run it.

Alternatively, you can do a quick CLI test:

jupyter nbconvert --execute --ExecutePreprocessor.timeout=600 --to notebook examples/tabular.ipynb

Please refer to and for more details on how to contribute to the fastai project.

Building From Source

If for any reason you can't use the prepackaged packages and have to build from source, this section is for you.

  1. To build pytorch from source follow the complete instructions. Remember to first install CUDA, CuDNN, and other required libraries as suggested - everything will be very slow without those libraries built into pytorch.

  2. Next, you will also need to build torchvision from source:

    git clone
    cd vision
    python install
  3. When both pytorch and torchvision are installed, first test that you can load each of these libraries:

    import torch
    import torchvision

    to validate that they were installed correctly

    Finally, proceed with fastai installation as normal, either through prepackaged pip or conda builds or installing from source ("the developer install") as explained in the sections above.

Installation Issues

If the installation process fails, first make sure your system is supported. And if the problem is still not addressed, please refer to the troubleshooting document.

If you encounter installation problems with conda, make sure you have the latest conda client (conda install will do an update too):

conda install conda

Is My System Supported?

  1. Python: You need to have python 3.6 or higher

  2. CPU or GPU

    The pytorch binary package comes with its own CUDA, CuDNN, NCCL, MKL, and other libraries so you don't have to install system-wide NVIDIA's CUDA and related libraries if you don't need them for something else. If you have them installed already it doesn't matter which NVIDIA's CUDA version library you have installed system-wide. Your system could have CUDA 9.0 libraries, and you can still use pytorch build with cuda9.2 libraries without any problem, since the pytorch binary package is self-contained.

    The only requirement is that you have installed and configured the NVIDIA driver correctly. Usually you can test that by running nvidia-smi. While it's possible that this application is not available on your system, it's very likely that if it doesn't work, than your don't have your NVIDIA drivers configured properly. And remember that a reboot is always required after installing NVIDIA drivers.

  3. Operating System:

    Since fastai-1.0 relies on pytorch-1.0, you need to be able to install pytorch-1.0 first.

    As of this moment's pre-1.0.0 version (torch-nightly) supports:

    Platform GPU CPU
    linux binary binary
    mac source binary
    windows source source

    Legend: binary = can be installed directly, source = needs to be built from source.

    This will change once pytorch 1.0.0 is released and installable packages made available for your system, which could take some time after the official release is made. Please watch for updates here.

    If there is no pytorch preview conda or pip package available for your system, you may still be able to build it from source.

    Alternatively, please consider installing and using the very solid "0.7.x" version of fastai. Please see the instructions.

  4. How do you know which pytorch cuda version build to choose?

    It depends on the version of the installed NVIDIA driver. Here are the requirements for CUDA versions supported by pre-built pytorch-nightly releases:

    CUDA Toolkit NVIDIA (Linux x86_64)
    CUDA 9.2 >= 396.26
    CUDA 9.0 >= 384.81
    CUDA 8.0 >= 367.48

    So if your NVIDIA driver is less than 384, then you can only use cuda80. Of course, you can upgrade your drivers to more recent ones if your card supports it. You can find a complete table with all variations here.


A detailed history of changes can be found here.


Copyright 2017 onwards,, Inc. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. A copy of the License is provided in the LICENSE file in this repository.

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