Chords by number
Roman numerals name a chord by its position in the key. In the key of C, C is the first chord (I), F is the fourth (IV) and G is the fifth (V). Move to the key of G and the same numerals become G, C and D. The numbers do not change, which is why musicians describe progressions with them.
Reading the symbols
- Uppercase (I, IV, V): major chords.
- Lowercase (ii, iii, vi): minor chords.
- ° (vii°): diminished. + is augmented.
- 7, maj7, ø7 after the numeral: a seventh chord. V7 is the dominant 7th.
The pattern of a major key
Every major key has the same pattern: I ii iii IV V vi vii°, which is major, minor, minor, major, major, minor, diminished. Stack thirds on each note of the scale and that is what falls out. In C that gives C, Dm, Em, F, G, Am and B°. Learn the pattern once and you can build the chords of any key.
Minor keys
The natural minor pattern is i ii° III iv v VI VII. A minor: Am, B°, C, Dm, Em, F, G. The major V (E in A minor) is often borrowed from harmonic minor, because it pulls harder back to the tonic.
Beyond the key
The top level adds chords from outside the key. Borrowed chords come from the parallel minor: iv, ♭III, ♭VI and ♭VII. Secondary dominants (V7/vi, V7/ii, V/V) are dominant chords that aim at another chord of the key, making that chord feel like a temporary home.
How to practise
- Warm-up: I, IV, V, ii and vi in friendly keys.
- Working set: every chord of the scale, in more keys and in minor.
- Heavy lift: exact spelling in every key, plus sevenths and borrowed chords. Use the focus setting to drill one kind at a time.
The chords in every key chart shows the full table. Learn where chords sit on the circle of fifths, spot a key from its chords with name that key, and learn the degree names with scale degrees.
Frequently asked questions
What are Roman numeral chords?
A way of naming chords by their place in the key instead of their letter. In C major, C is I, F is IV and G is V. The numbers stay the same in every key, so a progression like I–V–vi–IV can be played anywhere.
Why are some numerals uppercase and some lowercase?
Uppercase means a major chord (I, IV, V) and lowercase means minor (ii, iii, vi). A small circle means diminished (vii°). The case tells you the chord quality.
What are the chords in a major key?
I, ii, iii, IV, V, vi and vii°. In C major that is C, Dm, Em, F, G, Am and B°. The pattern major, minor, minor, major, major, minor, diminished is the same in every major key.
What are the chords in a minor key?
i, ii°, III, iv, v, VI and VII (natural minor). In A minor: Am, B°, C, Dm, Em, F, G. Songs often use a major V (E) borrowed from harmonic minor.
What does V7 or Imaj7 mean?
A seventh chord on that degree. V7 is the dominant 7th (G7 in C major). Imaj7 is a major 7th (Cmaj7). In a major key the seventh chords are Imaj7, ii7, iii7, IVmaj7, V7, vi7 and viiø7.
What does V/V mean?
A secondary dominant: the V chord of the V chord. In C major, V is G, so V/V is D (or D7). It is a strong chord from outside the key that pulls towards G.
What does ♭VII mean?
A major chord built on the flattened 7th note. In C major that is B♭. It is borrowed from the parallel minor and is very common in rock and pop.