This app was mentioned in 3 comments, with an average of 1.33 upvotes
Obviously much more robust than something I hacked together when I was trying to "get it". Is Lefty friendly though. Any feedback would be greatly appreciated.
https://play.google.com/store/apps/details?id=com.guitar_calculator
Similar Android app: https://play.google.com/store/apps/details?id=com.guitar_calculator
A related (possibly?) android app
https://play.google.com/store/apps/details?id=com.guitar_calculator