How can I tell which homebrew formulae are upgradable?

homebrew

Solution

Per homebrew code on github, this shows all apps that can be updated:

brew outdated

`brew help` does not list the command, but it is documented in `man brew`.

Problem

I know when I `brew update`, it lists all `==> Updated Formulae`, but when I've updated several times without running `brew upgrade`, how do I get a list of all apps that could be upgraded?

Original source