Roman Numeral Analysis

Once you can read notes and build chords, the next step is understanding how chords work together. Roman numeral analysis is the shorthand musicians use to do exactly that: it labels each chord by its scale degree within the key, so a progression can be understood independent of the key it happens to be in.

Numbers instead of letters

Instead of writing "C, then F, then G," we number the chords by where their root sits in the scale. In C major, C is built on the first degree, F on the fourth, and G on the fifth, so we write I, IV, V. Move that same idea to G major and the shapes change, but the analysis stays the same. The Roman numerals describe the relationships between chords, which is why they transfer to any key.

Reading case and symbols

The exact numeral tells you the chord's quality through a few simple conventions:

• UPPERCASE means a major chord: I, IV, V.
• lowercase means a minor chord: ii, iii, vi.
• lowercase with a small circle means a diminished chord: vii°.

Every major key produces the same fixed pattern of qualities when you build a triad on each scale degree: I major, ii minor, iii minor, IV major, V major, vi minor, and vii° diminished.

The seven diatonic chords in C major

What the numerals tell you: function

Beyond quality, Roman numerals reveal each chord's function, its role in the pull between tension and rest:

• Tonic (I) is home. It sounds settled and at rest.
• Subdominant (IV and ii) moves away from home, opening the harmony up.
• Dominant (V and vii°) creates tension that wants to resolve back to I.

This tension-and-release cycle, tonic to subdominant to dominant and back to tonic, is the backbone of countless songs.

Analysing a progression

Take the classic progression C – F – G – C. Look up each root in the table: C is I, F is IV, G is V, and C is I again. So the analysis is I – IV – V – I: leave home, build tension, resolve. Here it is on the staff as stacked triads.

Inversions and sevenths

Numerals can carry extra detail. Small figures show inversions, which chord tone is in the bass: a first-inversion tonic is written I6, and a second-inversion dominant is V64. Added notes appear as figures too, so a dominant seventh chord is V7. You can add these later; the plain triad numerals are enough to start hearing how harmony moves.

Try entering I – IV – V – I in the player above, then swap the V for vi to hear the difference between a dominant pull and a gentler landing. Listening while you read the numerals is the fastest way to make the labels feel like music.