@Schaick : Great minds think alike, indeed.

I like your more comprehensive chart organized by key and the Nashville number system. I organized mine by chord rather than key because that's just how my mind works at a jam. Maybe it's my guitar background.

Great find on that chart showing the guitar chord fingerings with pictures! I play some of those chords differently and I see other guitarists play other chords differently, so folks should be aware that there is more than one way to finger a guitar chord. Eventually, you'll get used to the way that the guitarists at the jams you attend play certain chords.

Just to clarify...the relative minor column on my chart indicates a note to play instead of the 5th, if the relative minor chord (same name as the note in that column) is being played instead of the major chord.

I created my chart as primarily a practice tool. Hopefully, playing the right notes will become second nature before too long.

I've updated my chart and thought I'd share...it's sort of a hybrid of my original chart and @Schaick 's chart. Again, I did this as a practice aid, not really for use at a jam, though I will likely keep it in my back pocket, just in case I get stuck.

DanielB said
Good looking chart!  I'd say laminate a copy and keep it tucked in your case.  

I do have one question though.. Do fiddlers or bluegrass players use a different variation of the Nashville Number System?  The version I've seen (some years ago, at least) used "Arabic" numerals instead of "Roman" and a minus sign "-" to show minor, so instead of I IV V vi, it looked like 1 4 5 6-.  

I always thought the break from Roman numerals was kind of sensible, since we usually would say the "five" or the "four" instead of the "Vee" or "Eye-Vee", and on a cramped and hastily scribbled chart, it can be hard sometimes to tell if someone meant you are supposed to play the IV chord, or a I chord and then a V chord.  

Nashville Number System wasn't covered when I took music, but I met a couple players over the years who used it.  Some of it, like the dots over the numbers on a song chart to tell what beats to play on, I never quite "got", but most of it seemed easy enough to figure out.  I never had a teacher who used it or was in a band that used it, so I never actually learned the details or nuances of it.  And I also might be confusing it with some other system, perhaps.

Your table though, at least appears to be done in the "traditional" (18th century) theory notation, with Roman numerals and "m" to indicate a minor chord?  So I'm wondering if maybe there is a different NNS or a hybrid that is used sometimes?

In any case, though.. It's a nice little table, easy to read and a lot of info packed into a small space.  Kudos, KindaScratchy!

If you google "Nashville Number System" you'll find images of charts, some of which use Roman numerals and some use Arabic numerals. I guess I based my chart on the first chart or two that I found in my original google searching for chord charts.

Although I've been playing guitar for close to 40 years, I had never heard of the Nashville Number System until recently. I wish that I had learned it many years ago. Nonetheless, I'm finding it very helpful now. Better late than never!

I added the chord spellings to my chart because, in the past, I relied on guitar chord fingering charts and never gave much thought to what notes make up each chord. Now, with fiddle and mandolin, I need to know what notes go with which chords in order to sound respectable when improvising.