What size does basic Bash/WSL subsystem on Windows occupy?

On a virtual machine running Win10 Insider Edition (Fast Ring) Version 1703 Build 16176.1000 I ran Disk Cleanup then restarted.

I viewed Used Space on my C drive, installed Windows Subsystem for Linux (Beta), restarted, then ran BASH and triggered the Ubuntu on Windows download.

Once the files had downloaded and unpacked and the initial setup was complete I measured disk space again.

Disk usage increased just over 600MB between the two measurements.

At first I thought you were asking how much current space is being taken up from the WSL install rather than how much it will require for initial install.

How Large My Current Installs Are...

Over time updates will undoubtedly have the default install growing larger over time. Also as you use WSL and mature your environment -- installing dependencies, it will grow over time as well.

Newer Install - WSL2 - Ubuntu

My semi-new install is under 2GB (for now...) I've got brew on it, fresh rvm, zsh, just the basics for now.

Under Windows' Apps & Features it lists Ubuntu "WSL2" as taking up 1.92 GB

ncdu reports 1.7 GiB (~1.82GB) which is pretty close to what Windows reports.

Older Install - WSL - Legacy "Bash on Ubuntu on Windows"

My older install is at 5GB -- this has nvm, rvm, vscode-remote, a bit of tons of project dependencies installed, etc. Most of which my newer install doesn't yet have.

P.S.

Measuring WSL Size

If you're like me and landed here from google trying to "What size WSL is using on your Windows machine" I've asked a separate question and answered it here: How Much Disk Space is WSL Using On Windows?

Smaller Options?

If you're looking for a custom WSL which may be smaller you can look into: https://github.com/RoliSoft/WSL-Distribution-Switcher as found in this question: