Roman Numeral Converter

Convert chord progressions ⇄ Roman numerals, then transpose, inspect, hear, and visualize the result.

Music Theory + Classic

Key Scale / Mode Accidentals

Chord progression

Supports common triads, sevenths, extensions, diminished/augmented, sus/add chords, and slash chords.

Result

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Recent conversions

Accuracy note: Roman-numeral labels follow the selected key/mode and the converter's stated notation rules. Functional interpretation can be context-dependent, especially for chromatic harmony.

Privacy: Core calculations and audio preview run in your browser. Recent history uses session storage only.

A Roman Numeral Converter for music helps you translate chord progressions into Roman numeral notation and convert Roman numerals back into real chord names for any supported key or mode.

For example, in C major:

C – G – Am – F

becomes:

I – V – vi – IV

The same Roman numeral pattern can then be moved into another key. In G major, I – V – vi – IV becomes:

G – D – Em – C

This makes Roman numeral notation especially useful for songwriting, transposition, harmonic analysis, arranging, and learning how chord progressions work independently of a specific key.

The tool also includes a separate Classic Numbers mode for converting ordinary integers such as 49 or 2026 into traditional Roman numerals. The music converter remains the main feature because it is designed specifically for chord progressions and harmony.

If you want to build a progression first and then inspect its theory, the Chord Progression Calculator provides a broader chord-building workflow.

How to Convert Chords to Roman Numerals

Start by choosing the key of your progression.

Then select the appropriate scale or mode and enter your chord sequence.

For example:

C G Am F

with C major selected produces:

I V vi IV

The converter determines where each chord root sits relative to the tonic and then combines that scale-degree relationship with the chord quality.

A typical workflow is:

Select the key.
Choose the scale or mode.
Enter your chord progression.
Convert the chords.
Review the Roman numerals.
Check the degree, chord quality, and chord tones.
Change key if you want to transpose the progression.

If you want a deeper explanation of the notation itself, the guide to Roman Numeral Chords explains how scale degrees are represented in harmonic analysis.

How to Convert Roman Numerals Back to Chords

The converter also works in reverse.

Suppose you enter:

I – V – vi – IV

and choose D major.

The result is:

D – A – Bm – G

If you change the key to E major, the same pattern becomes:

E – B – C#m – A

The Roman numeral sequence remains unchanged because the harmonic relationships remain the same.

This is one of the biggest advantages of Roman numeral notation: it separates the structure of the progression from the individual chord names.

If your main goal is to move existing chord names into another key, the Chord Transposer provides a more direct transposition workflow.

Understanding I, ii, iii, IV, V, vi, and vii°

In a major key, the basic diatonic triad pattern is:

Scale Degree	Roman Numeral	Chord Quality
1	I	Major
2	ii	Minor
3	iii	Minor
4	IV	Major
5	V	Major
6	vi	Minor
7	vii°	Diminished

In C major, that becomes:

I = C
ii = Dm
iii = Em
IV = F
V = G
vi = Am
vii° = Bdim

This reference is useful because once you understand the numerical pattern, you can recreate the same progression in any major key.

The same idea also applies to minor keys and modes, although the chord qualities and scale-degree relationships change.

For examples of how these patterns work in real progressions, the Diatonic Chord Progressions guide provides a useful next step.

Why Some Roman Numerals Are Uppercase and Others Lowercase

Uppercase and lowercase letters help communicate chord quality.

In common Roman numeral notation:

Uppercase usually represents a major chord.
Lowercase usually represents a minor chord.
A small degree symbol, such as vii°, represents a diminished chord.
A half-diminished seventh chord can be written with ø7.

For example:

C – Dm – G7 – C

in C major becomes:

I – ii – V7 – I

The Roman numeral tells you the scale degree, while the letter case and extra symbols tell you more about the chord itself.

This is more informative than simply writing:

1 – 2 – 5 – 1

because the Roman numerals preserve chord-quality information.

How Seventh and Extended Chords Are Written

Roman numeral notation can also represent seventh chords and common extensions.

Examples include:

G7 in C major → V7

Dm7 in C major → ii7

Cmaj7 in C major → Imaj7

Bm7♭5 in a suitable context → viiø7

The exact notation depends on the chord and analytical convention being used.

The converter preserves common chord-quality information so a seventh chord does not get reduced to a plain triad label.

For example:

Dm7 – G7 – Cmaj7

in C major can be shown as:

ii7 – V7 – Imaj7

This makes the converter useful for jazz, R&B, soul, gospel, and other styles where seventh chords are central to the harmonic language.

How Non-Diatonic Chords Are Represented

Not every chord in a song must belong to the selected scale.

Suppose you are in C major and use:

C – Bb – F – G

The Bb chord is outside the seven basic notes of C major.

Instead of incorrectly forcing it into an ordinary diatonic degree, the converter can represent its altered root as:

♭VII

So the progression becomes:

I – ♭VII – IV – V

Accidentals such as ♭ and # before Roman numerals indicate that the chord root is lower or higher than the corresponding diatonic scale degree.

These altered chords are common in rock, pop, modal harmony, film music, and many other styles.

A chord outside the key is not automatically wrong. If you want to explore more advanced ways to replace or color expected harmony, the guide to Chord Substitution covers several useful techniques.

Roman Numerals in Major, Minor, and Modes

The selected mode matters because the available scale degrees and chord qualities can change.

For example, C major and C Dorian both have C as their tonic, but they do not contain the same notes.

That means the same chord can receive a different interpretation depending on the selected scale context.

The converter supports major, minor, and modal systems so you are not forced to analyze every progression as if it belonged to a major key.

This is especially useful when working with Dorian, Mixolydian, Phrygian, Lydian, Locrian, harmonic minor, or melodic minor material.

Minor-key analysis can also become more complicated because natural, harmonic, and melodic minor introduce different versions of some scale degrees.

For that reason, the converter should be treated as a context-aware theory tool rather than a universal one-label answer for every possible piece of music.

Use Roman Numerals to Transpose Chord Progressions

Roman numerals make transposition much easier.

Imagine this progression in C major:

C – Am – F – G

Roman numerals:

I – vi – IV – V

Now change to A major.

The new chords become:

A – F#m – D – E

The Roman numerals remain:

I – vi – IV – V

This lets you preserve the harmonic pattern while adapting the actual chord names to a singer, instrument, arrangement, or production.

You can also use the Circle of Fifths Progressions page to explore how keys and chord relationships connect more broadly.

Roman Numerals vs the Nashville Number System

Roman numeral analysis and the Nashville Number System both describe chords relative to scale degrees, but they use different notation conventions.

Roman numeral notation typically uses symbols such as:

I – V – vi – IV

while the Nashville Number System might express a similar progression numerically as:

1 – 5 – 6m – 4

Both systems help musicians work independently of a single key.

Roman numerals are widely used in theory and harmonic analysis, while Nashville-style numbers are especially practical for performance, arranging, and quick key changes.

If you want to compare the two systems, read the guide to the Nashville Number System.

Music Roman Numerals vs Classic Roman Numbers

Music-theory Roman numerals and ordinary Roman numerals use similar symbols but solve different problems.

In classic Roman-number notation:

49 = XLIX

100 = C

2026 = MMXXVI

In music theory:

I, ii, V7, vi, ♭VII

describe scale degrees and chord qualities.

That means:

C major chord = I

does not mean the number one in the ordinary mathematical sense. It means the chord is built on the first scale degree of the selected key.

The tool keeps these two tasks in separate modes to avoid confusion.

How to Read the Theory Breakdown

The converter can show more than the final Roman numeral.

For each chord, you can inspect:

Chord name
Scale degree
Roman numeral
Chord quality
Chord tones
Whether the root is diatonic or altered
A concise harmonic-role hint

For example:

G7 in C major

may appear as:

V7 — G B D F

This tells you both the structural role and the actual notes inside the chord.

For a broader analysis of a complete sequence, use the Chord Progression Analyzer after converting the progression.

Accuracy and Analysis Limitations

Roman numeral conversion is straightforward when the key, mode, chord roots, and chord qualities are clearly defined.

However, full harmonic analysis can be more ambiguous.

A chromatic chord may act as a borrowed chord, secondary dominant, modal color, passing harmony, or part of a modulation. The chord symbol alone does not always provide enough information to determine one definitive function.

Different analytical traditions may also use slightly different notation.

For this reason, the converter separates calculated relationships from broader harmonic interpretation.

The calculated pitch relationship may be clear even when the musical function depends on context.

Roman numerals should therefore be used as a powerful analytical framework, not as proof that only one interpretation is possible.

Privacy and Browser Processing

The core conversion and theory calculations are designed to run directly in your browser.

You do not need to upload audio, create an account, or provide personal information simply to convert chords or Roman numerals.

Temporary conversion history can be stored for convenience during the browser session and cleared from the tool when no longer needed.

Frequently Asked Questions

What is a Roman numeral converter for music?

It converts chord names into scale-degree-based Roman numeral notation and can convert those Roman numerals back into chord names for a selected key.

How do I convert chords to Roman numerals?

Choose the key and mode, enter your chord progression, and the converter determines each chord’s scale degree and quality.

What does I–V–vi–IV mean?

It means chords built on the first, fifth, sixth, and fourth scale degrees. In C major, that produces C–G–Am–F.

Why is vi lowercase?

Lowercase Roman numerals commonly indicate minor chords. In a major key, the sixth diatonic triad is minor.

What does vii° mean?

It represents a diminished chord built on the seventh scale degree.

What does ♭VII mean?

It indicates a chord whose root is one semitone lower than the ordinary seventh scale degree of the selected key.

Do Roman numerals change when I transpose a song?

Usually the Roman numeral pattern stays the same when the entire progression is transposed consistently. Only the actual chord names change.

Can Roman numerals represent seventh chords?

Yes. Examples include V7, ii7, Imaj7, and viiø7.

Does every chord have one correct Roman numeral?

Not necessarily. The label depends on the key and harmonic context, especially for chromatic chords and modulations.

Are Roman numerals and the Nashville Number System the same?

They are related scale-degree systems but use different notation conventions and are often used in different musical contexts.

Can I convert ordinary numbers too?

Yes. The separate Classic Numbers mode converts integers into traditional Roman numerals and can convert valid Roman numerals back into integers.

Convert Chords, Understand the Pattern, and Move It Anywhere

The Roman Numeral Converter is most useful when you think of it as more than a notation translator.

It reveals the structure behind the chord names.

A progression such as:

G – D – Em – C

and:

D – A – Bm – G

may look different on the page, but both share the same:

I – V – vi – IV

framework.

Once you understand that relationship, it becomes much easier to transpose songs, compare progressions, analyze harmony, communicate with other musicians, and turn one chord sequence into multiple arrangements.

If you want to create a fresh progression after learning the notation, the Random Chord Progression Generator can provide new harmonic ideas that you can then convert and analyze using Roman numerals.