Roman Numerals
The universal language of progressions · I ii iii IV V vi vii°
Roman numeral analysis is how musicians describe chord progressions without naming a key. Instead of writing "C – F – G – C", we write "I – IV – V – I" — the numerals describe each chord by its position in the key, so the same notation works whether the song is in C, G, B♭, or F♯. Once you can read Roman numerals fluently, you can transpose a progression to any key on the fly.
I – V – vi – IV in Roman numerals
The four-chord pop progression that has powered hundreds of hits. Switch the key below and watch the chord names change while the Roman numerals stay the same.
Toggle voice leading in the player to hear it smooth out, or learn voice leading →
The ivory paper and ink palette on this page is inspired by music-color synesthesia, roman numerals maps to ivory paper and ink, reflecting its scholarly, text-like precision.
About Roman Numerals
Roman numerals encode two pieces of information in a single symbol: which scale degree the chord is built on, and whether that chord is major, minor, diminished, or half-diminished. Uppercase numerals (I, IV, V) name major chords. Lowercase numerals (ii, iii, vi) name minor chords. A small circle (vii°) indicates a diminished chord; a slashed circle (iiø7) indicates a half-diminished seventh. With those four marks, you can describe any diatonic chord in any key.
In a major key, the seven diatonic chords always follow the same quality pattern: I (major), ii (minor), iii (minor), IV (major), V (major), vi (minor), vii° (diminished). That pattern is built into the major scale itself — stacking thirds from each degree of the scale automatically produces those qualities. The pattern for natural minor is different but equally fixed: i, ii°, ♭III, iv, v, ♭VI, ♭VII. Memorize those two patterns and you have a complete map of every diatonic chord in tonal music.
The real payoff is transposing. If someone tells you a song goes "I – V – vi – IV", you do not need to know what key they meant — you just need to know which key *you* want to play it in. In C major that becomes C–G–Am–F. In G it becomes G–D–Em–C. In E♭ it becomes E♭–B♭–Cm–A♭. The numerals stay put; the chord names follow whichever key you pick. This is why pro session players think in numbers, not letters: it lets them change key mid-rehearsal without rewriting a chart.
Variations
ii – V – I in Roman numerals
The single most-played progression in jazz, written in the same notation that works for any key.
Pachelbel — I, V, vi, iii, IV, I, IV, V
Eight chords in Roman numerals. Try the same eight functions in any key below.
I – vi – IV – V (50s doo-wop)
Capital, lowercase, capital, capital — the qualities tell you the chord quality without naming the key.
i – ♭VI – ♭VII – i (minor key)
The flat signs mark chords whose roots come from outside the natural-minor scale.
Famous songs & pieces
- Pachelbel's Canon in D, Johann Pachelbel (I – V – vi – iii – IV – I – IV – V written in Roman numerals)
- Don't Stop Believin', Journey (I – V – vi – IV — the Axis progression in E)
- Let It Be, The Beatles (I – V – vi – IV verse in C)
- No Woman No Cry, Bob Marley (I – V – vi – IV in C, looped throughout)
- Somewhere Over the Rainbow, Harold Arlen (I – iii – IV – iv chromatic motion)
- Hallelujah, Leonard Cohen (The lyric famously narrates this very progression as the song plays it — IV, V, vi, back to IV)