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Roman numeral analyzer: what are these chords doing?
Type a chord progression and see what each chord is doing: its Roman numeral, its job in the key, how it connects to the chords around it, and why the progression works. Everything is worked out from the chords — and where the key itself is uncertain, the tool says so and lets you read the chords in each key that fits.
Roman numeral analyzer
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Analyse a progression
Type the chords in order. Each one gets its Roman numeral and its job in the key; select a chord to see why.
Separate chords with spaces, bar lines | or dashes -. Slash chords like G7/B are kept.
Enter a progression above, or pick an example. Each chord appears here with its Roman numeral and its job in the key, followed by how the chords connect and why the progression works.
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From chords to what they do
A chord symbol says which notes sound. A Roman numeral says where the chord sits in a key, and that is what explains its behaviour. C – Am – F – G7 – C reads I – vi – IV – V7 – I in C major. The analysis works in that order: first the key, from the key finder’s evidence; then each chord’s numeral; then what each chord does, and how the chords lead into each other.
Tonic, predominant and dominant
The chords of a key do three jobs. Tonic chords are home; predominant chords (ii and IV) set up the dominant; dominant chords (V and vii°) pull back to the tonic. Its chords run tonic → predominant → dominant → tonic (C → F → G7 → C): the basic circuit of harmonic function. vi and iii share two notes with I and can stand in for it, which is why the tool labels them tonic too. Harmonic function explains the three groups.
The key changes the numerals
The same chords can do different jobs in different keys. C – Am – F – G is I – vi – IV – V in C major and III – i – VI – VII in A minor: the G that is the dominant in C major is the subtonic in A minor, with no leading tone to pull it home. When the chords alone do not settle the key, the tool shows that, and you can read the progression in each key that fits. Relative keys explains why both fit.
Secondary dominants: pointing at another chord
A chord from outside the key often has a job inside it. In C – A7 – Dm – G7 – C, Its C♯ is a semitone below D, and the next chord is Dm, the ii chord of C major. A7 points to it for a moment without leaving the key. The tool calls a chord a secondary dominant only when the chord it points at actually follows; the same A7 going somewhere else is described as outside the key instead.
Borrowed chords: colour, not a new key
Some chords come from the parallel key. A♭ (♭VI) and B♭ (♭VII) are borrowed from C minor: colour from outside the key, while C stays home. They are not in C major, and that does not make C major the wrong key: borrowed chords keep the tonic, while a modulation establishes a new one.
Minor keys and the raised seventh
In Am – Dm – E7 – Am, G♯ is A minor’s raised seventh: natural minor would have G, and no leading tone. That raised note is what makes E7 a real dominant in A minor, and why the numeral is V7 rather than v7.
Inversions and slash chords
A slash chord puts a particular note in the bass, and the numeral shows it with figures: C/E – F – G7/B – C reads I6 – IV – V6/5 – I. G7/B has its third (B) in the bass: first inversion, written V6/5. A bass note that is not one of the chord’s own notes is not an inversion, and the tool says so rather than inventing a figure. Chord inversions explains the figures.
Resolutions and cadences
The tool lists how neighbouring chords connect — dominant to tonic, predominant to dominant, a secondary dominant to its target, the plagal IV → I, a dominant swerving to vi. It names a cadence only for the last two chords, because a cadence is the pair that ends a phrase and the end of what you typed is the only phrase ending a chord list shows. The same G7 → C in the middle is called a dominant-to-tonic resolution. And if a progression ends on its dominant, the tool says what happens when it repeats, and marks that as conditional: If the progression repeats, G at the end resolves to C at the start — dominant to tonic across the repeat.
What it reads, and what it does not
The same chord symbols as the chord transposer and the key finder: triads, sevenths, sus, 6 and add9 chords, with slash basses. A chord it cannot read is named and left out, and the result says the analysis is partial. It does not detect key changes partway through, modal progressions or the blues as keys of their own, and it explains harmony only — a chord list has no melody or rhythm. For a full written explanation in prose, the chord progression analyzer offers a report.
Not sure what a chord is? Name it from its notes with the chord identifier. Want to hear common progressions in every key? Try the chord progression explorer. Every key’s chords are listed on its key page.