In a GitHub repository you can see “language statistics”, which displays the percentage of the project that’s written in a language. It doesn’t, however, display ho
I have talked to customer support and confirmed that this can not be done on github.com. They have passed the suggestion along to the Github team though, so hopefully it will be possible in the future. If so, I'll be sure to edit this answer.
Meanwhile, Rory O'Kane's answer is a brilliant alternative based on cloc and a shallow repo clone.