Roman numerals
Name chords by their degree with Roman numerals so a progression works in any key.
Chord names change with the key. Numbers do not. Roman numerals let you write a progression once and play it in any key.
Numbering the chords
Chords are numbered with Roman numerals on the degree of their root. The numeral also shows the quality:
- UPPERCASE = major (I, IV, V);
- lowercase = minor (ii, iii, vi);
- lowercase + ° = diminished (vii°);
- uppercase + “+” = augmented (III+).
In a major key the chords are I – ii – iii – IV – V – vi – vii°.
| Key | I | ii | iii | IV | V | vi | vii° |
|---|---|---|---|---|---|---|---|
| C | C | Dm | Em | F | G | Am | B° |
| G | G | Am | Bm | C | D | Em | F♯° |
| D | D | Em | F♯m | G | A | Bm | C♯° |
| F | F | Gm | Am | B♭ | C | Dm | E° |
| B♭ | B♭ | Cm | Dm | E♭ | F | Gm | A° |
Key-independent
A progression written in numerals is key-independent: I–IV–V is C F G in C, G C D in G and E A B in E. This is the basis of transposing chords (lesson 5.7). Writing a progression out in numerals is Roman numeral analysis.
Other systems
- All uppercase with “m” for minor (IIm, IIIm, VIm), used in some books, including Goodman.
- The Nashville number system with Arabic numbers (Module 15).
This site uses the uppercase/lowercase style everywhere, as in the Key Chords tool. A chord outside the key is written with an accidental before the numeral: ♭VII in C is B♭ (Module 14).
Write I–vi–IV–V in G, D and F, then play its roots.
New terms
Tools
- Key Chords: The chords of every major and minor key, chosen on the circle of fifths, with bass boxes and common progressions.