Roman Numeral Chord Converter
Turn Roman numeral progressions into real piano chord names in any key. Pick a common preset, enter custom numerals, hear each chord, and jump straight into practice.
What Roman numerals mean on piano
Roman numerals describe chords by scale degree, not by a fixed note name. That lets musicians talk about the same harmonic pattern in every key. A chart written as I–V–vi–IV works in C (C–G–Am–F), G (G–D–Em–C), and every other major key — only the note names change.
Uppercase vs lowercase numerals
Uppercase Roman numerals (I, IV, V) typically indicate major triads in a major key. Lowercase numerals (ii, iii, vi) indicate minor triads. A ° symbol marks diminished quality, as in vii°. Reading case correctly helps you predict chord quality before you transpose.
Major and minor key patterns
In a major key, the diatonic triads are I, ii, iii, IV, V, vi, and vii°. In natural minor, the pattern shifts to i, ii°, III, iv, v, VI, and VII. When you pick a key in the converter, these defaults are applied automatically so I–V–vi–IV always lands on the right major and minor chords.
Diminished and altered chords
The vii° chord is the leading-tone diminished triad — Bdim in C major. You can also enter accidentals such as bVI or #iv°, and suffixes like dim7 or m7b5. The converter spells each chord using the note names that match your selected key.
Transposing progressions to any key
Transposition keeps the harmonic relationships while changing note names. That is why Nashville numbers and Roman numerals are so useful for singers, songwriters, and pianists. Use “Show in all keys” to compare how the same progression looks across every major or minor key at once.
Common progressions to know
I–V–vi–IV is everywhere in pop. I–IV–V–I is a classic cadence. ii–V–I is essential in jazz. vi–IV–I–V adds an emotional start on the relative minor. The preset menu includes these patterns so you can hear and convert them instantly.
Practice tips after converting
After you convert a progression, play each chord slowly and say both the numeral and the chord name aloud. Loop playback at a comfortable tempo, then open the Progression Trainer or Go Practice to build muscle memory. Connecting theory labels to physical shapes is what makes Roman numerals stick.
Frequently asked questions
- What are Roman numerals in music?
- Roman numerals label chords by their position in a key. I is the home chord, IV is the subdominant, V is the dominant, and vi is the relative minor. Uppercase numerals usually mean major quality; lowercase means minor.
- How do I convert I–V–vi–IV to chord names?
- Choose your key — for example C major — and enter or select the progression. I–V–vi–IV in C becomes C – G – Am – F. Change the key and the same numerals produce the matching chords in that key.
- Why are some Roman numerals uppercase and others lowercase?
- Case shows the expected chord quality in a key. In C major, I, IV, and V are uppercase major chords, while ii, iii, and vi are lowercase minor chords. vii° is diminished. The converter applies these defaults unless you add an explicit suffix.
- Can I use Roman numerals in minor keys?
- Yes. Select a minor key such as Am or Dm. Natural minor uses its own diatonic pattern — for example i, ii°, III, iv, v, VI, and VII — and the converter transposes your progression accordingly.
- Does this work with seventh chords and extensions?
- The converter supports common suffixes such as 7, maj7, m7, dim, sus2, sus4, add9, and more. Enter numerals like ii7, V7, or viim7b5 and the tool resolves them to the matching chord type in your chosen key.