What it is for
Roman numeral analysis describes each chord according to the scale degree on which it is built and therefore its function in the key (see "Roman numerals in analysis" for notation conventions). This entry is a working method, valid for a chorale, a sonata or a pop song.
Convention of the archive: in minor, the Roman numerals refer to the natural minor (in A minor: i, ii°, III, iv, v, VI, VII); the major dominant with the raised leading tone is written V (or V7) and is flagged as borrowing from the harmonic minor.
Step 1: find the key
- Look at the key signature and the cadences (especially the last one).
- In minor look for the altered leading tone (in A minor G♯) that appears on the dominants.
- In pop: the chord on which the song "rests" and the note on which the chorus phrases end.
Step 2: identify each chord
- Gather all the notes of a stretch with the same harmony (often a beat or a bar).
- Eliminate the non-chord tones (passing tones, neighbor tones, suspensions, appoggiaturas): they are usually on short notes, by step, on weak beats, or they resolve.
- Arrange the remaining notes in thirds to find the root.
- Determine the quality (major, minor, diminished, augmented, sevenths).
Step 3: write the numeral and the inversion
- Roman numeral of the scale degree of the root, uppercase or lowercase according to quality.
- Inversion with figures (6, 6/4, 6/5, 4/3, 4/2), looking at the lowest note, not the root.
- In pop you can use slash notation (I/3, V/7) or Roman numerals with bass (I6 = C/E).
Step 4: recognize special functions
- Secondary dominants: a major or dominant seventh chord on a degree that is normally minor (in C: E7 = V7/vi, A7 = V7/ii, D7 = V7/V).
- Borrowed chords (modal interchange): chords from the parallel mode (in C: Fm = iv, A♭ = ♭VI, B♭ = ♭VII).
- Chromatic chords: Neapolitan sixth (♭II6), augmented sixths, diminished sevenths.
- Cadential six-four: I6/4 followed by V over the same bass note (often written V6/4–5/3).
Step 5: mark cadences and modulations
- Cadences: perfect authentic (PAC), imperfect authentic (IAC), half cadence (HC), deceptive (DC), plagal.
- Modulation: when a new center is confirmed by a cadence. Find the pivot chord, which belongs to both keys, and write it with a double analysis (for example in C → G: Am = vi in C = ii in G).
Step 6: look at the structure
Group the chords into phrases (where are the cadences?) and into functions (T – PD – D – T). A classical phrase goes: tonic prolongation → predominant → dominant → tonic.
Example 1 (C major, 4/4, one chord per bar)
| Bar | Chord | Analysis | Comment |
|---|---|---|---|
| 1 | C | I | tonic |
| 2 | Am | vi | tonic prolongation |
| 3 | Dm7 | ii7 | predominant |
| 4 | G7 | V7 | dominant, half cadence or continuation |
| 5 | C | I | |
| 6 | E7/G♯ | V6/5/vi | secondary dominant of vi |
| 7 | Am | vi | |
| 8 | A7 | V7/ii | secondary dominant of ii |
| 9 | Dm | ii | |
| 10 | Fm/A♭ | iv6 | borrowed from the parallel minor (bass A♭) |
| 11 | C/G – G7 | I6/4 – V7 | cadential six-four |
| 12 | C | I | perfect cadence |
Example 2 (A minor, numerals relative to the natural minor)
Am – G – F – E7 – Am: i – VII – VI – V7 – i. The VII (G) and the VI (F) are diatonic to the natural minor; E7 is the dominant with the leading tone G♯ taken from the harmonic minor. This is the Andalusian cadence closed on the tonic.
Example 3 (pop, G major)
G – D/F♯ – Em – C – G/B – Am7 – D: I – V6 – vi – IV – I6 – ii7 – V. The bass descends by step G–F♯–E–C–B–A–D: the inversions come from the bass line.
Common mistakes
- Analyzing passing tones as chords (too many Roman numerals).
- Confusing the bass with the root (Am/C is not "III," it is i6 in A minor or vi6 in C).
- Not recognizing tonicization: calling an E7 that goes to Am "III" in C (it is V7/vi).
Exercise
Analyze in Roman numerals: a Bach chorale (8 bars), the first theme of a Mozart minuet and the progression of a favorite song of yours. Write the function (T, PD, D) under each chord as well.
Related entries
Roman numerals in analysis, Figured-bass labels for inversions in harmonic analysis, Diatonic functions, Cadences, Secondary dominants, Modal interchange, Modulation techniques, Analysis of a jazz tune from a lead sheet.