How to Understand Harmonic Analysis — Roman Numerals Explained

Learn Roman numeral analysis — the universal language of harmony. Identify chords by scale degree, understand chord function, and analyze any piece of music.

Roman Numerals Are the GPS of Harmony

Instead of saying 'C major chord followed by F major chord,' musicians say 'I to IV.' Roman numerals describe function — what a chord does — regardless of key. I-IV-V-I in C major (C-F-G-C) is functionally identical to I-IV-V-I in G major (G-C-D-G). Learning this system is the single most powerful upgrade to your theory understanding.

The Seven Diatonic Chords

Build a triad on each scale degree. In major: I (tonic, major), ii (supertonic, minor), iii (mediant, minor), IV (subdominant, major), V (dominant, major), vi (submediant, minor), vii° (leading tone, diminished). Uppercase = major. Lowercase = minor. Diminished gets a degree symbol.

Chord Functions

Tonic (I, vi, iii): stable, home, restful. Subdominant (IV, ii): moving away from home, building energy. Dominant (V, vii°): maximum tension, demanding resolution back to tonic. The most fundamental harmonic motion in Western music: I → IV → V → I. Tonic → Subdominant → Dominant → Tonic.

Analyze Any Song

Take any lead sheet or chord chart. Identify the key. Label each chord with its Roman numeral. Look for patterns: I-V-vi-IV is everywhere. ii-V-I is the jazz turnaround. I-vi-IV-V is the 1950s progression. Once you see the Roman numerals, the song's harmonic structure becomes transparent — and you can transpose it to any key instantly.

Frequently Asked Questions