Convert a chord progression into Nashville Number System notation, or turn a number chart back into chords in any key.
The Nashville Number System writes chords as scale-degree numbers instead of letter names, so a progression can be read and played in any key without rewriting it. This tool converts in both directions.
Chords to Numbers
Key (e.g. C):
Chord Progression (e.g. C G Am F):
Numbers: —
Numbers to Chords
Key (e.g. G):
Numbers (e.g. 1 5 6m 4):
Chords: —
What the Nashville Number System Is
Instead of writing “C, G, Am, F,” a Nashville number chart writes “1, 5, 6m, 4.” Since the numbers represent scale degrees rather than fixed notes, the same chart works in any key: a session player can transpose on the fly just by knowing the new key’s root note.
How to Use This Calculator
- Chords to Numbers: enter the key and a space-separated chord progression to get the number chart.
- Numbers to Chords: enter a key and a space-separated number chart (use “m” for minor, like 6m) to get the actual chords.
Example: in the key of C, the progression C G Am F converts to 1 5 6m 4. That same 1 5 6m 4 progression in the key of G becomes G D Em C.
This converter handles basic major and minor triads (like C, Am, F#m). Extended chords (7ths, sus chords, etc.) aren’t recognized and will show as non-diatonic or unrecognized.
Number-to-Chord Reference Table
In the key of C, the seven diatonic chords are: 1 = C, 2m = Dm, 3m = Em, 4 = F, 5 = G, 6m = Am, and 7 = B diminished. In the key of G, the same numbers give 1 = G, 2m = Am, 3m = Bm, 4 = C, 5 = D, 6m = Em, and 7 = F# diminished. Learn the pattern once and you can read a chart in any key.
Why Players Use Number Charts
Singers often need a song moved to a different key. With a number chart, a band can switch keys instantly without rewriting anything. Numbers also make it easy to see common patterns, such as 1-5-6m-4 in pop songs or 1-4-5 in blues and country.
Did You Know?
- The Nashville Number System was developed by session musicians in Nashville in the late 1950s and became especially associated with country music studio work.
- A diatonic major-key progression uses these default qualities by scale degree: 1 major, 2 minor, 3 minor, 4 major, 5 major, 6 minor, 7 diminished.
Frequently Asked Questions
What if a chord doesn’t fit the key?
A chord borrowed from outside the key (a chromatic or non-diatonic chord) will be labeled as non-diatonic rather than forced into a number, since it doesn’t map cleanly to a scale degree.
How do I show a minor chord in numbers?
Add a lowercase “m” after the number, like 6m for a minor sixth chord.
Can I use flats or sharps in the key or chords?
Yes, both # and b are recognized, such as F# or Bb.
Does the number 1 always mean the tonic chord?
Yes. The 1 is the chord built on the key’s root note, and every other number counts up the major scale from there.
How are 7th chords written in Nashville numbers?
Players add the extension after the number, for example 5⁷ or 1maj7. This converter handles basic triads only, so add the extensions by hand on your chart.