Roman Numeral Analysis
Roman numerals describe chords by their position in a key, not by their note name. Uppercase means major, lowercase means minor, and the ° symbol means diminished. This system lets musicians discuss harmony in any key.
How It Works
In any major key, there are 7 chords built from the scale. Roman numerals number them I through vii. The case tells you the chord type: uppercase (I, IV, V) = major, lowercase (ii, iii, vi) = minor, ° symbol (vii°) = diminished.
For example, in C major: I = C, ii = Dm, iii = Em, IV = F, V = G, vi = Am, vii° = Bdim. In G major: I = G, ii = Am, iii = Bm, IV = C, V = D, vi = Em, vii° = F#dim. The Roman numerals are the same — only the note names change.
Why Roman Numerals Matter
Roman numerals reveal the deep structure of music. The progression I–V–vi–IV sounds the same in every key — it is the feel of "Let It Be," "No Woman No Cry," and hundreds of other songs. This abstraction lets musicians communicate about harmony without being tied to a specific key.
In ChordColor
When you select a key and lock it, the KEY row displays all 7 diatonic chords with their Roman numerals. Switch between scales and modes to see how the pattern changes — Dorian gives i–ii–III–IV–v–vi°–VII, natural minor gives i–ii°–III–iv–v–VI–VII.