Installed Anaconda 4.3.1 (64-bit) which contains Python 3.6 but pip3 missing, cannot install tensorflow

If you do not have another environment installed python 3+ will default to just pip I believe since pip3 is just an alias for pip.

pip install --upgrade pip

or You can do it with the associated Python binary too; if it executable as python3, then use that:

python3 -m pip install --upgrade pip

after that check:

pip --version 

otherwise just try pip-3.6

for tensorflow on conda:

pip install --ignore-installed --upgrade https://storage.googleapis.com/tensorflow/windows/gpu/tensorflow_gpu-1.0.1-cp35-cp35m-win_amd64.whl 

for python 3.6 due to conda providing the 3.5 one: from

pip install https://testpypi.python.org/packages/db/d2/876b5eedda1f81d5b5734277a155fa0894d394a7f55efa9946a818ad1190/tensorflow-0.12.1-cp36-cp36m-win_amd64.whl

Since this wheel had a version that is undesirable we could instead install the wheel directly from gohlke's windows binaries repository :
download the wheel for python 3.6 from here and then install the wheel:

cd to the directory containing .whl file:

pip install some-package.whl