To install Dart SDK is easy by package manager on Mac, Windows or Linux.  Package manger is very convenient way to maintain your packages.

Install Dart on Mac

Install Homebrew if not installed on your Mac.

Run commands

brew doctor
brew update
brew tap dart-lang/dart
brew install dart

To upgrade

brew upgrade dart

Check what you have installed

brew info dart

Install Dart on Windows

Install Chocolatey on Windows

Run commands

choco install dart-sdk

To upgrade

choco upgrade dart-sdk

Install Dart on Linux

Install using apt-get

sudo apt-get update
sudo apt-get install apt-transport-https
sudo sh -c 'curl https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add -'
sudo sh -c 'curl https://storage.googleapis.com/download.dartlang.org/linux/debian/dart_stable.list > /etc/apt/sources.list.d/dart_stable.list'

What’s in the Dart SDK

• dart – The standalone VM
• dart2js – The Dart-to-JavaScript compiler (used only for web development)
• dartanalyzer – The static analyzer
• dartdevc – The Dart development compiler (used only for web development)
• dartdoc – The API documentation generator
• dartfmt – The Dart code formatter
• pub – The Dart package manager

More information about the Dart SDK see the official README file

Dart SDK on Github