The Nashville Number System (NNS) is a way to write chord charts that was popularized in the Nashville studio scene, but now commonly used by music directors and performing musicians in worship and cover band settings.

Recording session origins

Since session musicians are typically hired to create the parts of a song on the fly, number charts were devised as a simple way to communicate the structure of a song--the chord changes, the form, the arrangement--as succinctly and clearly as possible.

You can read more about the origins in this Nashville Number System article (Wikipedia).

Chords as Numbers

A hallmark of the Nashville Number System is that chords are expressed with numbers instead of letters. Those numbers are in reference to the major key that best fits the song. If you're familiar with the concept of "Movable Do" (Wikipedia), you'll feel right at home with number charts. If not, below we'll give a quick primer.

Why would they do that!?

Well, for one, a lot of times the final key of a song has not been determined, and that gets worked out in the studio based on where it's comfortable for the range of the vocalist. With chords-as-numbers, the song could be tried in several different keys, without having to transpose on-the-fly or rewrite the chart.

You might be thinking:

Surely these A-list studio musicians could transpose on the fly

I'm sure they could. But when you're trying to get that magic take, you want musicians feeling and not thinking.

Simple example

In the key of C, a common progression might be C | F | G | C. You might recognize this as a I - IV - V - I progression, as it would commonly be described in music theory.

In NNS, you would write this as: 1 4 5 1

What if I'm not in the key of C? What if I need to play or notate more than these simple chords?

If you were in the key of G, for example, this 1 4 5 1 progression would be played as G | C | D | G.

We have a handy, printable PDF reference that shows all of the chords in each key, and what numbers they correspond to.

Making your own number chart

JotChord™ is an app for making beautifully-formatted NNS-style number charts. You simply type the numbers, and as you're typing, a PDF chart is continuously updated with the numbers you've typed.

Is it really that easy?

Yeah, it is. You can get more sophisticated if you want to, but a surprising number of popular songs use only a few chords, with simple Intro-Verse-Chorus-Verse-Chorus-Bridge-Chorus-Chorus type forms.