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.
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.