The Nashville number system, for guitar
Nashville numbers write a chord progression as scale degrees instead of chord names, so one chart works in every key. How to read it, how it relates to Roman numerals, and why session players use it.
What it is
Instead of writing the chords of a song as letters, the Nashville system writes them as the number of the scale degree each chord is built on. In C major, C is 1, F is 4, G is 5, Am is 6m. A chart that says 1 – 5 – 6m – 4 is C – G – Am – F in C and G – D – Em – C in G. Change the key, keep the chart.
Reading a Nashville chart
- A bare number is a major chord: 1, 4, 5.
- A number with m is minor: 2m, 3m, 6m.
- A 7 after a number is a dominant seventh: 57.
- A flat or sharp before the number moves the root outside the key: b7 is the chord a whole step below the root, the rock-riff chord.
- A number with a diamond around it is held; a number with a slash is a bass note: 1/3 is the 1 chord with the 3rd in the bass.
Nashville vs Roman numerals
They are the same idea in two notations. Roman numerals — I ii iii IV V vi vii° — show major and minor by case. Nashville uses Arabic numbers and writes minor explicitly with an m. Session players prefer Nashville because it is faster to write and read on a chart in a dark studio; theory books prefer Roman because it carries more detail. Guitar Theory Studio shows both and lets you toggle.
The three progressions that cover most songs
- 1 – 5 – 6m – 4: Pop Anthem. C – G – Am – F in C.
- 1 – 4 – 5: Rock / Country / Blues Backbone. C – F – G in C.
- 2m – 5 – 1: ii-V-I Turnaround. Dm7 – G7 – Cmaj7 in C.