Roman numerals in analysis: classical, jazz and pop systems

Definition

Roman numerals indicate on which scale degree a chord is built, regardless of the key. “I–V–vi–IV” is the same progression in C (C G Am F), in E (E B C#m A) or in Bb (Bb F Gm Eb). It is the tool that lets you understand the function of a chord and transpose on the fly.

Classical system (Kostka-Payne, Aldwell-Schachter)

• Uppercase = major triad (I, IV, V); lowercase = minor (ii, iii, vi).
• ° = diminished (vii°); + = augmented (III+); ø = half-diminished (viiø7).
• Figures for inversions and sevenths: V7, V6/5, V4/3, V4/2; I6, I6/4 (see Figures).
• Secondary dominants: V/V (D in C), V7/ii (A7), vii°7/V (F#°7).
• Modal borrowing: bVI, bVII, iv in major (Ab, Bb, Fm in C).
• Special chords: N6 or bII6 (Neapolitan sixth), It+6, Fr+6, Ger+6 (augmented sixths), Cad6/4 (cadential 6/4).
• Key: indicated on the left (“C:”); in modulations the pivot chord is written with a double label (C: vi = G: ii).

In C major: I (C), ii (Dm), iii (Em), IV (F), V (G), vi (Am), vii° (B°).

In A minor (with raised leading tone): i (Am), ii° (B°), III (C), iv (Dm), V (E), VI (F), vii° (G#°). With natural minor v (Em) and VII (G).

Jazz system (Berklee)

• The numeral is always uppercase and the quality is given by the symbol: IMaj7, IIm7, IIIm7, IVMaj7, V7, VIm7, VIIm7(b5).
• bVIIMaj7, bVI7, SubV7 (tritone substitute: Db7 = SubV7 of C).
• Related II: IIm7/V (Am7 before D7, which is V7/V).
• Arrows (→) for resolutions by fifth and square brackets for ii–V pairs.

Advantage: you immediately read the symbol of the actual chord. Disadvantage: the case no longer shows the quality at a glance.

Pop and songwriting system

Similar to the classical one (lowercase for minor chords), often without figures: I–V–vi–IV, vi–IV–I–V, i–bVI–bIII–bVII. The typical debate: in minor-key songs, do you analyze relative to the minor tonic (i–VI–III–VII) or to the relative major (vi–IV–I–V)? Choose based on where the ear hears rest; Hooktheory uses the actual mode (Aeolian, Dorian…).

Reading a progression

1. Find the key (key signature, first and last chord, cadences).
2. Write the scale and the degrees.
3. Label the diatonic chords, then the chromatic ones: ask yourself “whose dominant is it?” (secondary) or “which mode does it come from?” (borrowing).
4. Group by function: T (I, vi, iii), PD/S (IV, ii), D (V, vii°).

Examples in real songs

• “Let It Be” (The Beatles, C): C G Am F = I V vi IV.
• “Don't Stop Believin'” (Journey, E): E B C#m A = I V vi IV.
• Pachelbel's Canon (D): D A Bm F#m G D G A = I V vi iii IV I IV V.
• “Zombie” (The Cranberries, E minor): Em C G D = i VI III VII.
• “Autumn Leaves” (G minor, jazz system): Cm7 F7 BbMaj7 EbMaj7 Am7(b5) D7 Gm = IVm7 bVII7 bIIIMaj7 bVIMaj7 IIm7(b5) V7 Im (in G minor) or IIm7 V7 IMaj7 IVMaj7 in the relative Bb major.
• “Creep” (Radiohead, G): G B C Cm = I III IV iv (III = secondary dominant of vi left unresolved, iv = borrowed from the minor).

Exercise

1. Analyze with Roman numerals the four main chords of three songs you love and write the function next to each.
2. Transpose “I V vi IV” and “ii V I” into all 12 keys, out loud, for 5 minutes a day.
3. In FL Studio create a chord pattern, then transpose everything by 3 semitones: the Roman numerals don't change, only the names of the notes do.

Related topics

Diatonic functions; Inversion figures in analysis; Secondary dominants; Modal interchange; Chord symbols; Pop progressions and loops.