At GrassTrax we use the Nashville Number System (NNS) for the chord charts that come with our tracks, so you can have a simple chord progression document that will work in any key.

The NNS is used by many musicians worldwide, and especially professional studio musicians who work with a variety of artists and need to be able to easily change the key they play in.

At its simplest, NNS replaces chords with numbers. The advantage here is that you can change which key you are playing the song in without having to rewrite the chord chart.

How does it work? It’s all based on degrees of the major scale. In the key of C, for instance, you have these notes: C D E F G A B

If you assign a number to each of those notes, C becomes 1, D=2, E=3, and so on. See the chart at right for all the major scales for the natural notes.

An NNS chord chart, then, would look like this:

1                             4
Bile them cabbage down, down
1                               5
Turn them hoecakes round…

Instead of a traditional chord chart like this:

G                            C
Bile them cabbage down, down
G                               D
Turn them hoecakes round…

If you’re using an NNS chart and you need to play the song in a new key, you just change the key in your head, and play the new chords. Viola!