You might want to check out allsides.com [1] which gives a rating for where media sources lie on a left-right spectrum
Personally, I find the https://realclearpolitics.com model of just putting headlines from different outlets in a list to be more useful than outsourcing some sort of "bias rating" and "fact-checking" to YAMO (Yet Another Media Outlet).
I think the real subtext of this chart isn't so much to portray any particular outlet further to the left or right than it is, but rather to boost the credibility of fringe outlets.
That being said, I do appreciate that allsides uses an interesting method to blind bias surveys to help categorize. But sometimes things don't always line up.
While I agree that NPR puts out a lot content that can be described as 'lefty', NPR News feels pretty straight down the middle.