Understanding the Nashville Number System

Musicians communicate in all kinds of ways, but one of the most important ways bluegrass musicians communicate is through the Nashville Number System.

How does the Nashville Number System work?

The Nashville Number System is a simple way to indicate a song’s chord changes by using numbers instead of the typical letters, so you aren’t tying them to any specific key. If you know a song’s chord progression using the Nashville Number System, you can play it in any key. This is particularly handy in bluegrass jams, where the person who calls the song, or the person who sings it, typically gets to pick the key.

Suppose you’re jamming with somebody who wants to play “Blue Ridge Cabin Home” but you don’t know the song. They’ll tell you, “The chord progression is just I, IV, V, I repeated.” (Those are Roman numerals, by the way.)

That’s all you need to know, whether they sing it in the key of G or the key of D.

What they’re telling you is that the song starts on the I chord. The first change is to the IV chord, then to the V chord, then back to the I chord.

What do chord numbers mean?

Every key has a I chord, known as the “root.” It is the chord that corresponds to the key. In the key of G, the I chord is G. In the key of D, the I chord is D.

The IV chord is three letters up from that. (In music theory they probably say it’s three scale degrees up from the tonic or something like that, but hey, this is bluegrass.) In the key of G, the IV chord is C because G > A > B > C. In the key of D, the IV chord is G because D > E > F > G.

The V chord is just one letter up from the IV chord. In the key of G, the V chord is D. In the key of D, the V chord is A.

So, the chord progression for “Blue Ridge Cabin Home” would be:

  • Key of G: G, C, D, G
  • Key of D: D, G, A, D

As you play more and jam with others more, you will find that most bluegrass songs use just a few of these go-to chords (the I, IV and V are by far the most common). You will come to recognize the sound of these chord changes. You’ll hear a bluegrass song on your iPhone and be able to identify when the song jumps from the I to the IV, or from the I to the V. You may not know what key it’s being played in, but you’ll know how those chord changes sound. The next time somebody calls that song at a jam, you’ll know how to play it even if they choose a different key.

Congratulations, you’re becoming a musician.

To get there, you will need to know your Is, IVs and Vs (and perhaps a few other chords) in all the major keys.

Nashville Number System chart for bluegrass guitar

The following chart shows all seven major keys, and the Roman numerals show which number represents which chord in each key.

KeyIIIIIIIVVviVIIb
GGABCDEmF
AABC#DEF#mG
BBC#EbEF#AbmA
CCDEFGAmBb
DDEF#GABmC
EEF#AbABC#mD
FFGABbCDmEb

Note that this chart differs slightly from others you may come across, because it is specific to bluegrass. The final column contains not the seventh chord, but the flatted seventh chord. In bluegrass you will almost never use the seventh chord, so there was little point in including it on the chart. Many bluegrass songs, however, contain a nice bluesy chord change from the root to the flatted seventh and back again (for example, G-F-G or D-C-D).

Likewise, we include the sixth chord as a minor chord using small Roman numerals (vi), because you will rarely play the sixth as a major chord.

You may also come across charts that similarly show the II and the III chord as minor chords (ii and iii), but in bluegrass it is much more common to play those chords as major chords, so we left them as is.

Nashville Number System hand signals

One of the great things about the Nashville Number System is that you can indicate chord changes without yelling out “G!” or “C!” or “D!” in the middle of a song. Often at a bluegrass jam, when a song is unfamiliar to some in the circle, one person will stand where everyone can see and use hand signals to indicate the chord changes.

The hand signals are pretty straightforward. An upraised index finger is the symbol for the I chord, four fingers is the symbol for the IV chord, and a full five fingers is the symbol for the V chord. With someone leading this way, everyone can just keep an eye on those hand signals and know when to change chords. Once you’ve been through the verse and chorus once or twice, you’ll know the changes and can take your eyes off the signals.

How to memorize the Nashville Number System

The best way to memorize the Nashville Number System is to pick the most common bluegrass keys or chord shapes, and get to know the I, IV and V chords in those keys.

As long as you have a capo, you can get through pretty much any bluegrass song playing out of G, C or D chord shapes. So you really just need to know the I, IV and V chords in those keys. They are:

KeyI chordIV chordV chord
GGCD
CCFG
DDGA

It doesn’t take much jamming or practice to get really comfortable with these changes that are used over and over again. Once you know them, then it really doesn’t matter what key you are playing in. For example, if somebody calls a song in the key of C, you’ll know immediately that you go to the F chord on IV, and to the G chord on V. If somebody is using hand signals to indicate the changes, you know that four fingers equals F and five fingers equals G.

If the key is D, then four fingers equals G and five fingers equals A.

If the key is G, then four fingers equals C and five fingers equals D.

If there are any unusual or less common chord changes in the song, you should be able to figure them out fairly quickly using those other three chords as reference points.

The Nashville Number System is like a language that bluegrass musicians speak. It is universal in the bluegrass world, which makes it worth getting to know. Once you understand it and have some practice using it, you can show up at a jam in North Carolina or Colorado or San Francisco and quickly pick up any song that’s unfamiliar. Just ask, “What are the changes?” and when they come back at you with numbers instead of letters, you’ll know just what to do.

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