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Remember the last time you had to quickly transpose a tune? Your chart, featuring chords like “D major” or “A minor” felt rather useless at that point, didn’t it?

What if I told you there is a system, used by professional recording musicians, that simplifies song charts and allows you to transpose and improvise with much less effort?

The Nashville number system uses numerals instead of letters to indicate a chord. With this system anyone can transpose a tune in a matter of seconds, without needing many music theory notions. Its simple but precise symbol method allows anyone to experiment with improvisation, making it a great tool for session musicians and jazz players.

How does it work? – The theory premise 

To understand how the Nashville number system works we must take a step back and recall the structure of a major scale. This is formed by seven notes, each one representing a grade. 

For example, if we consider C major, we’ll have the notes C, which is the first grade of the scale, D, which is the second grade, E, which is the third grade, and so on, right to B, the seventh and last grade of the scale.

Now, if we build a triad on each grade, using only notes deriving from our major scale, we’ll have:

1. C – E – G = a major chord
2. D – F – A = a minor chord
3. E – G – B = a minor chord
4. F – A – C = a major chord
5. G – B – D = a major chord
6. A – C – E = a minor chord
7. B – D – F = a diminished chord

The triads built on a major scale are the foundation of the method. Let’s see in detail what I mean.

What do numbers stand for?

In this system, a number represents a certain grade of the scale. The number 1, for example, stands for the first grade of the scale. If we are in C major, the number 1 will therefore indicate the chord/note C. If we are in G major, it will stand for the chord/note G, and so on.

Let’s assume you are a guitarist or a pianist and that the numbers in your chart represent chords to be played to accompany a singer. Here are some examples for you to familiarize with the method.

• Key: A major

1  4  1  5 

A major  D major A major E major

Why are these all major chords? If you’re in doubt, get back to the scheme representing the triads built on the major scale. You will notice that we can only form major triads on the grades 1, 4 and 5. 

• Key: C major

1 5 2 5

C major G major D minor G major

Why is number 2 a minor chord? Because we can only form a minor triad on the second grade of a major scale. You don’t necessarily have to remember this detail, though, as more often than not you will find a “-” or an “m” right beside the number, to remind you that chord has to be minor.

Our 2, therefore, could be written as 2- or 2m.

• Key: F major

1 3 4 5

F major A minor Bb major C major

The Nashville number system and minor keys

There is a tiny complication: if our tune is in a minor key, we have to be careful about the triads built on each grade, which are obviously different from the ones formed on a major scale.

Although, as I mentioned before, minor, augmented, and diminished chords are often highlighted with specific symbols, it is advisable to know what triads we can form on the two most common minor scale: natural and harmonic.

The natural minor scale

Let’s assume we are in A minor, an “easy” key, with no alterations. 

The natural A minor scale will be:

A B C D E F G

1 2 3 4 5 6 7

Now, let’s build some triads on these grades.

1. A – C – E = a minor chord
2. B – D – F = a diminished chord
3. C – E – G = a major chord
4. D – F – A = a minor chord
5. E – G – B = a minor chord
6. F – A – C = a major chord
7. G – B – D = a major chord

Following this scheme, in A minor key, the number 2 will stand for a B diminished chord. The number 4 will stand for a D minor chord, and so on.

The harmonic minor scale

To keep things easy, let’s stick to the A minor key.

Here’s the harmonic A minor scale:

A B C D E F G#

1 2 3 4 5 6 7

Here’s the list of triads we can form on a harmonic scale:

1. A – C – E = a minor chord
2. B – D – F = a diminished chord
3. C – E – G# = an augmented chord
4. D – F – A = a minor chord
5. E – G#- B = a major chord
6. F – A – C = a major chord
7. G#- B – D = a diminished chord

For example, in A minor, number 7 will be G# diminished; number 4 will be D minor; number 1 will be A minor, and so on.

Having introduced diminished and augmented chords, let’s see what symbols can be used to alter the nature of a common major triad in the Nashville number system.

Common symbols used in the system

There are tons of different possibilities when it comes to chords. Are they major, minor, augmented, diminished? Do we have to add a specific bass?

The Nashville number system allows us to indicate how a chord should be altered, inverted or “completed” with simple symbols. Let’s see the most common ones.

• Δ = major 7th 
• – or m = minor
• ° or dim = diminished
• + or aug = augmented
• ø = half diminished
• 1/3 = play a 1 chord (grade 1 of the scale) with a 3 (third grade of the scale) bass
• 7 = dominant seventh

An example: “When The Saints Go Marching In”

Here is an example of the classic gospel When The Saints Go Marching In written using the Nashville number system.

Key: E major 4/4

1 . . . 1 . . . 1 . . .

1 . . . 1 . . . 1 . . .

57 . . . 57 . . . 1 . . .

17 . . . 4 . . . 4 . . .

1 . . . 57 . . . 1 . . .

And here’s a classic chord chart:

| E | % | % | % | % | % | B7 | % | E | E7 | A | % | E | B7| E |

Why is the Nashville number system so valuable

As I have already mentioned, this system allows anyone to easily transpose a tune and improvise.

The fact we have numbers instead of notes, makes it easier for us to change the key we are playing in. For the same reason, jazz players will find this method exceptionally good to practice improvisation.

Last but not least, the flexibility of the system and the vast quantity of symbols you can easily add beside each number, allows you to include a lot of information (the nature of a chord, what bass should be played, and so on), almost like in a classical music sheet.