Tools
Roman numeral converter
Turn a chord progression into roman numerals, or numerals back into chords in any key. Type either one: the key is detected, every chord is numbered against it, and the whole chart can be read the other way with one tap — and heard on the instrument you choose.
ChordstoRoman numerals
Numerals or chords will appear here.
How to convert chords to roman numerals
- Find the key. A chord’s numeral depends entirely on the key it sits in: G is V in C major and I in G major. The tool scores every key against your chords and shows its best guess; change it and every numeral changes with it.
- Count each chord’s root up from the tonic. C, D, E, F, G, A and B in C major are degrees one to seven, written I to VII. A root outside the scale takes an accidental: B♭ in C major is ♭VII.
- Write the quality with the case. Upper case for a major chord (I, IV, V), lower case for a minor one (ii, iii, vi), a small circle for a diminished chord (vii°) and a plus for an augmented one (III+). Sevenths and extensions follow as they do on a chord symbol: V7, ii7, Imaj7.
- Read it back in any key. Type the numerals — or tap the swap button — choose a key, and the tool spells each chord the way that key spells it. Transposing a song is exactly this: numerals out of one key, chords into another.
How to read roman numerals
A roman numeral names a chord by its place in the key rather than by its root, which is what makes it portable: I–V–vi–IV is the same progression in every key, and a musician who knows the numerals can play it in any of them without a second chart. The numeral says the degree, the case says the quality, and anything after it — 7, maj7, ø7, sus4 — reads exactly as it would on a chord symbol. A bass note is written as a figured-bass mark for an inversion (I⁶ is the first inversion of I, V⁶₅ the first inversion of V7) or as a slash and a degree for anything else (I/2).
Minor keys follow one convention here: degrees are always counted against the major scale of the tonic, so A minor reads i, ii°, ♭III, iv, v, ♭VI, ♭VII, and its dominant E7 is V7. That is how the site’s course writes them, and it means a numeral produced by this tool can be pasted into any page of the site and mean the same chord. The table shows the seven diatonic chords of C major and A minor side by side.
| Degree | C major | A minor |
|---|---|---|
| 1 | IC | iAm |
| 2 | iiDm | ii°Bdim |
| 3 | iiiEm | bIIIC |
| 4 | IVF | ivDm |
| 5 | VG | vEm |
| 6 | viAm | bVIF |
| 7 | vii°Bdim | bVIIG |
Roman numerals or Nashville numbers?
Nashville numbers say the same thing with arabic numerals: 1 for the tonic, 5 for the dominant, an m for minor, and sevenths and extensions as superscripts. Session players use them because a number can be read at a glance and written in the margin of a lyric sheet; the case rule that carries quality in roman numerals is replaced by the m. The tool writes either, and reads either back.
I V vi IV→1 5 6m 4
C G Am F
Common progressions as numerals
The six progressions the site documents in every key, written as roman numerals, as Nashville numbers, and as the chords they give in C major. Open one to read it in eight keys and hear it on your instrument, or paste its numerals above to get it in any key.
Worked examples
Chords → numerals · C major
C G Am F→I V vi IV
Chords to numerals. C major is detected; each root is counted from C, and the minor chord takes lower case.
Chords → numerals · A minor
Am F C G→i bVI bIII bVII
vi IV I V · C major
The same four chords opening on the minor one. The tool reads them in A minor and offers the relative major as the other reading; which is right depends on where the song comes to rest.
Numerals → chords · E♭ major
ii7 V7 Imaj7→Fm7 B♭7 E♭maj7
Numerals to chords. A ii–V–I written in numerals, realised in E♭ major: the seventh chords keep their types, and the dominant is spelled B♭7 because E♭ major is a flat key.
Questions
- What are roman numerals in music?
- A way of naming chords by their position in a key instead of by their root. The tonic chord is I, the chord on the fifth degree is V, and so on up to VII. Because the numbers describe relationships rather than notes, a progression written this way is the same in every key, which is why musicians use them to analyse songs, to learn progressions, and to play in any key from one chart.
- Why are some numerals upper case and some lower case?
- The case carries the chord’s quality: upper case is major, lower case is minor, and a small circle after a lower-case numeral marks a diminished chord. In C major that gives I, ii, iii, IV, V, vi and vii°, the seven chords of the key. The tool applies the same rule to sevenths and extensions, so Dm7 in C is ii7 and G7 is V7.
- What does ♭VII or ♯iv° mean?
- A flat or a sharp before a numeral moves its root off the major scale of the key. B♭ in C major is ♭VII; F♯° is ♯iv°. These are the borrowed and chromatic chords a song brings in from outside its key, and the tool marks them so you can see at a glance which chords are diatonic and which are not.
- How are inversions and slash chords written?
- With figured-bass marks when the bass is a chord tone: I⁶ is a first-inversion tonic (C/E in C), I⁶₄ a second inversion (C/G), and V⁶₅, V⁴₃ and V⁴₂ are the three inversions of V7. When the bass is not a chord tone the tool writes a slash and the bass’s degree instead, so C/D in C major is I/2. Both forms are read back into chords.
- How does it handle minor keys?
- By counting every degree against the major scale of the tonic, the convention used throughout this site: A minor reads i, ii°, ♭III, iv, v, ♭VI, ♭VII, and E7 — the dominant of the minor key — is V7. Some textbooks number the natural minor scale instead, so that C in A minor is III rather than ♭III; if a chart you are reading does that, the chords are the same and only the accidentals differ.
- What is the difference between roman numerals and Nashville numbers?
- The same idea in arabic numerals: 1 to 7 for the degrees, an m for minor instead of lower case, and sevenths as superscripts (5⁷, 2m⁷). Nashville charts are what session musicians read on a recording date, because a number is faster to read and to write than a numeral. The tool writes and reads both; pick the one your band uses.
- Can I convert a whole song with lyrics?
- This tool works on a progression: a line or a few lines of chords. For a full sheet with lyrics, section labels or tab, use the chord transposer: paste the song, and its roman-numeral view writes the numerals over every line while the lyrics stay in place. It also transposes the sheet into any key and prints it.
- Is it free, and where do my chords go?
- It is free and needs no account. Everything happens in your browser: nothing you type is sent to a server or stored anywhere but in the address bar, which is what lets you share or bookmark a result.