The Nashville Number System Explained
Read and write chords as numbers (1, 4, 5, 6m) so one chart works in any key. The diatonic chart, the modifiers, worked examples, and how it pairs with a capo.
The Nashville Number System (NNS) writes a song's chords as scale-degree numbers — 1, 4, 5, 6m — instead of letters. Because the numbers describe each chord's role in the key rather than its name, one chart works in every key: change the key written at the top and the same numbers point at new chords, with nothing to rewrite. It's the common language of Nashville session players and most worship bands. Here's how to read and write it.
Where it comes from — and why it wins
The system was devised in the late 1950s by Neal Matthews Jr. of the Jordanaires (Elvis Presley's vocal group) as a fast way to chart recording sessions, and was extended by players such as Charlie McCoy. Its advantage is brutal efficiency: a singer decides to drop a song a whole tone, the leader says “same numbers,” and nobody rewrites anything — the one chart already serves a baritone and a soprano. That's why a session player can walk in, get handed numbers, and nail a song they've never heard.
The foundation: numbers come from the major scale
Number each note of the major scale 1 through 7 and build a chord on each. In every major key the qualities are always the same — this fixed pattern is the whole key to the system:
| Number | Quality | In the key of C | In the key of G |
|---|---|---|---|
| 1 | Major | C | G |
| 2m | Minor | Dm | Am |
| 3m | Minor | Em | Bm |
| 4 | Major | F | C |
| 5 | Major | G | D |
| 6m | Minor | Am | Em |
| 7° | Diminished | B° | F♯° |
Memorise one thing — 1, 4 and 5 are major; 2, 3 and 6 are minor; 7 is diminished — and you can decode any number chart in any key. A bare number defaults to the major triad; a minor chord is marked with an m or a minus sign (6m or 6−), and diminished with °.
Reading a number chart
Take the most common progression in popular music, the 1 – 5 – 6m – 4. Here is what those four numbers become in several keys — the same chart, different key at the top:
| Key | 1 | 5 | 6m | 4 |
|---|---|---|---|---|
| C | C | G | Am | F |
| G | G | D | Em | C |
| D | D | A | Bm | G |
| E | E | B | C♯m | A |
This is the payoff: to transpose, you change nothing on the chart — you just read the numbers against a new key. A guitarist can even capo to make the shapes easy while reading the very same numbers the keyboard player reads in concert pitch.
The modifiers you'll actually see
| On the chart | Meaning | Example in C |
|---|---|---|
| 6m, 2− | Minor chord | Am, Dm |
| 7° | Diminished | B° |
| 5 7 or 5⁷ | Add a 7th | G7 |
| 4maj7, 1maj7 | Major 7th | Fmaj7, Cmaj7 |
| 1/3 | Inversion — bass is the 3rd | C/E |
| 5/7 | Inversion — bass is the 7th degree | G/B |
| ◇ over a number | Hold / let ring | Hit once and sustain |
| ^ (marcato) | Short, accented stab | Staccato hit |
| Two numbers grouped in a bar | They share one measure | e.g. 1 then 4 within the same bar |
A push — hitting a chord an eighth-note before the downbeat — is shown with a small mark before the number (commonly a “<”). Pushes are where a lot of a song's feel lives, so charts mark the important ones and leave the rest to your ears.
A worked example
Here is a simple verse and chorus written in numbers, then read out in two different keys. The chart itself never changes — only the key at the top:
| Section | Numbers | In G | In D |
|---|---|---|---|
| Verse | 1 4 6m 5 | G C Em D | D G Bm A |
| Chorus | 4 5 1 6m | C D G Em | G A D Bm |
Hand that to a band in any key and they'll play it instantly. Hand them the same thing as letter chords and you'd be rewriting it every time a singer wanted a different key.
Using numbers with a guitar and capo
Numbers and capos are a perfect match. The band can stay in the concert key while you, the guitarist, capo up to play easy open shapes — still reading the same numbers, just fingering friendlier chords. Decide the key, then let the capo calculator find the easiest capo for it. Working from a letter chart instead? Transposing it first makes converting to numbers trivial.
Tips for getting fluent
- Drill the diatonic chords in your most-used keys (G, D, A, E on guitar) until 1‑4‑5‑6m is automatic.
- Hear the numbers, not just see them. The 5 has a strong pull home; the 6m is the “relative minor” sadness. Naming what you hear is the real skill.
- Write your own setlist in numbers. One chart per song then works for any singer, and any last-minute key change.
- Mark only the pushes and holds that matter. Over-notating defeats the purpose — the system is meant to be sparse.