Chord Detector
  1. Chord Detector
  2. Chord progression finder

Step 1: get the chords

Chord progression finder: get the chord progression of a song

This chord progression finder starts with the song itself. Paste a YouTube link or upload a file to get its chords and key, then drop them into the converter below to read the progression in Roman numerals.

Paste a link such as https://www.youtube.com/watch?v=…

or

MP3, WAV, OGG, M4A or FLAC · up to 50 MB · 15 minutes

First full song free with an account No card required First 60 seconds without signing up

  • Chords
  • Key
  • Roman numerals
  • Any of 24 keys

Step 2: free converter

Convert chords to Roman numerals

Type or paste the chords, pick the key and read the progression as numerals. It runs in your browser and needs no account.

Separate chords with spaces, commas or bars. Sevenths, sus, dim, aug and slash chords work.

Try a famous progression

Key: C major. 4 of 4 chords belong to it.

  • ICin key
  • VGin key
  • viAmin key
  • IVFin key

In C major, I is the home chord, V is the dominant, vi is the relative minor and IV is the subdominant. All 4 chords belong to the key.

Chords, keys and numerals at a glance

  • 24 keys12 tonics in major and minor, or let the converter suggest one
  • 7 chordsbelong to every key, each with its own numeral
  • 15 minlongest YouTube video or file Chord Detector reads
  • $0for the converter and for the first 60 seconds of chords

The short answer

In short

A progression finder lists the chords a song plays, in order, and names each one by its place in the key. Chord Detector reads the chords and the key from a YouTube link or an audio file, and the converter on this page turns them into Roman numerals such as I, V, vi and IV.

The idea

What a chord progression finder does, and what Roman numerals mean

A chord progression is the order of chords a song moves through, for example C, G, Am, F. Finding the progression of a recording means working that order out, then describing it in a way that does not depend on the key. The description is a Roman numeral: a number from I to VII for the step of the scale the chord is built on.

In C major the scale steps are C, D, E, F, G, A and B, so C is I, G is V, Am is vi and F is IV. Shift the whole song to D major and the chords become D, A, Bm and G, but the numerals stay I, V, vi and IV. That is why musicians say “it is a four-chord loop” and not “it is C, G, Am, F”.

The song page shows chord names, not numerals, so the two steps work together: YouTube to chords gets the names, and the converter above turns them into numerals.

One progression, three keys Same numerals, different chords
C major
  • IC
  • VG
  • viAm
  • IVF
D major
  • ID
  • VA
  • viBm
  • IVG
A major
  • IA
  • VE
  • viF#m
  • IVD

Reading numerals

How to read a Roman numeral

Case, small symbols and the chord suffix carry the whole chord, so a numeral is as exact as a chord name.

Uppercase and lowercase
Uppercase is a major chord, lowercase a minor one. In C major, V is G and vi is Am. A seventh chord keeps its number: V7 is G7 and ii7 is Dm7.
Degree sign and plus
A small circle marks a diminished chord, so vii° is Bdim in C major. A plus marks an augmented chord, so I+ is Caug.
Suffixes
What follows the chord name stays on the numeral: Imaj7 is Cmaj7, Isus4 is Csus4 and viiø7 is Bm7b5, the half-diminished chord.
Flats and sharps
A flat or sharp in front means the root is a semitone away from the scale step. In C major, bVII is Bb, because the scale has B and the chord sits a semitone lower.
Slash chords
The scale step of the bass goes after the slash. C/E in C major is I/3, since E is the third note of the scale. This page does not use the I6 shorthand, because C6 is also I6.
In key or borrowed
A chord is in key when every note it plays is in the scale. If one note is outside, the converter marks the chord borrowed and names the notes that fall outside the key.

How it works

How to find the chord progression of a song

Four steps from a link to a progression in numerals. The first two happen on our servers, the last two in your browser.

  1. Paste a link or upload a file

    Use a public video from youtube.com, youtu.be or music.youtube.com up to 15 minutes, or an MP3, WAV, OGG, M4A or FLAC file up to 50 MB. A private, age-restricted or region-blocked video cannot be fetched, so upload the audio instead.

  2. Chord Detector reads the chords and the key

    A trained model reads the whole spectrum of the mix, a decoder removes single-frame flicker and snaps changes to the beat, and a tuning correction handles tracks not tuned to A4 = 440 Hz. The key comes from those chords. Chords usually arrive in about twenty seconds.

  3. Read the chords on the song page

    Chords sit above the lyrics, next to the key, tempo and time signature. Without an account you see the chords of the first 60 seconds and the key of the whole song. A loop that repeats often shows its pattern within that minute.

  4. Paste them into the converter

    Copy the chord names of a verse or a chorus into the box above and keep the key on Auto, or pick the key from the song page. The numerals appear as you type. See song key finder for how the key is worked out.

The seven chords

The diatonic chords of a major and a minor key

Every key has seven chords built from its own scale, and these are the ones a progression finder counts as in key. The examples use C major and its relative minor, A minor, which share all seven chords.

Triads on each step of the scale. In minor songs the V is often a major chord (E in A minor), which the converter also counts as in key.
StepMajor keyChord qualityIn C majorMinor keyChord qualityIn A minor
FirstIMajorCiMinorAm
SecondiiMinorDmii°DiminishedBdim
ThirdiiiMinorEmIIIMajorC
FourthIVMajorFivMinorDm
FifthVMajorGvMinorEm
SixthviMinorAmVIMajorF
Seventhvii°DiminishedBdimVIIMajorG

Notice the shared chords: A minor uses the same seven chords as C major, only starting from A. That is why a loop such as Am F C G can be read as i VI III VII in A minor or as vi IV I V in C major. It is also why the converter names a runner-up when it suggests a key.

Patterns to know

Famous chord progressions in Roman numerals

Each card shows the numerals and one spelling in a key. Load any of them into the converter with the chips above it.

  • I–V–vi–IV

    The four-chord loop

    • IC
    • VG
    • viAm
    • IVF

    C G Am F in C major. The verse of ‘Let It Be’ moves through these four chords.

  • vi–IV–I–V

    The same chords, minor start

    • viAm
    • IVF
    • IC
    • VG

    Am F C G in C major. Starting the loop on vi makes it lean minor while the chords stay the same.

  • I–vi–IV–V

    The fifties progression

    • IA
    • viF#m
    • IVD
    • VE

    A F#m D E in A major, the chords of ‘Stand By Me’. In C major the same pattern is C Am F G.

  • ii–V–I

    The jazz cadence

    • ii7Dm7
    • V7G7
    • Imaj7Cmaj7

    Dm7 G7 Cmaj7 in C major. It is a staple of jazz standards and is usually played with seventh chords.

  • i–VI–III–VII

    The minor-key loop

    • iAm
    • VIF
    • IIIC
    • VIIG

    Am F C G in A minor. The numbers follow the natural minor scale, so VI is F and not bVI.

  • I–IV–V

    The 12-bar blues

    • IC
    • IVF
    • VG

    Twelve bars of I I I I IV IV I I V IV I V, so C C C C F F C C G F C G in C. Players often swap in sevenths: C7, F7 and G7.

Pachelbel’s Canon in D Eight chords, repeated

D A Bm F#m G D G A

  • ID
  • VA
  • viBm
  • iiiF#m
  • IVG
  • ID
  • IVG
  • VA

Why numerals

Why Roman numerals beat chord names

Names tell you which chords to play. Numerals tell you what the chords do, and that is what carries from one song to the next.

  • Transposing

    To move a song, keep the numerals and change the key. I V vi IV in G is G D Em C, no recalculation of each chord.

  • Comparing songs

    A song in C and a song in D can share one progression. Numerals show it at a glance, names hide it.

  • Talking to a band

    “Twelve-bar blues, I IV V” works in any key, so a singer can pick the key that fits their voice.

  • Spotting surprises

    A bVII or a bIII in an otherwise plain loop stands out in numerals. In names it looks like just another chord.

By style

Common chord progressions by style

These are patterns you will meet often, not rules. Styles overlap, and one song can use several.

Typical shapes, spelled in C major or A minor. Load any of them with the chips in the converter.
StyleTypical shapeChords
Pop and rockI V vi IV, vi IV I V, I vi IV VC G Am F, Am F C G, C Am F G
BluesThe 12-bar form on I, IV and VC7 F7 G7 in C
Jazzii V I, often with seventhsDm7 G7 Cmaj7
Minor-key songsi VI III VIIAm F C G

Find a chord progression by key

To get a chord progression by key, choose the key in the converter, tap a chip and the chords appear in that key. ii–V–I in G is Am7, D7 and Gmaj7; I–V–vi–IV in E is E, B, C#m and A. Spellings follow the key, so F# major gives F#, C#, D#m and B, while Gb major gives Gb, Db, Ebm and Cb.

By ear

How to find a chord progression by ear

You can check the result, or skip the upload, with an instrument and a few minutes.

  1. Find the home chord. It is the one a verse starts or ends on and the one that feels settled. That chord is I, or i in a minor song.
  2. Listen to the bass under each change. Play the bass note and count the scale steps up from the home note. A bass a fifth above is usually V, a fourth above is IV.
  3. Decide major or minor for each chord. Play both and keep the one that matches the song. Major gets an uppercase numeral, minor a lowercase one.
  4. Write the numerals, then test them. Type the chord names into the converter. If most chords are marked in key, the key is right; if many are borrowed, try the relative major or minor.

Shortcut: if the first chord of a loop is a minor chord and the key is major, the loop probably starts on vi. Am F C G in C major begins on vi, so it is vi IV I V.

Stuck on a single shape? The chord identifier names it from its notes.

Limits

Where the numerals are reliable and where to check

Chord detection is automatic, so treat the chord names as a strong first answer and confirm them by ear. The numerals are only as good as the chords and the key you give them.

Works well on

  • A loop or verse of triads and seventh chords in one key.
  • Chords copied from a song page, a chart or your own notes.
  • Sus, dim, aug, 6th and slash chords: all of them get a numeral.
  • Both major and minor songs, in any of the 24 keys.

Check by ear when

  • The recording is ambiguous between major and minor. The detector can prefer one, so check the first verse.
  • A chord is marked borrowed. It may be a real borrowed chord, or the key may be wrong.
  • The song changes key. The converter reads one key at a time, so run each section with its own key.
  • Auto names two keys that fit equally. Relative major and minor share chords, so the chord progression finder lets the home chord decide.

More tools

Related tools for chords and keys

FAQ

Questions about finding a chord progression

What is a progression finder?

It shows which chords a song plays, in order, and how they relate to its key. On this page Chord Detector finds the chords and the key from a YouTube link or an audio file, and the converter turns them into Roman numerals such as I, V, vi and IV.

How do I find the chord progression of a song?

Paste a public YouTube link or upload an MP3, WAV, OGG, M4A or FLAC file in the box at the top of the page. Chord Detector returns the chords above the lyrics and the key. Copy a few bars of chords into the converter, leave the key on Auto or pick the key from the song page, and read the numerals.

Does the song page show Roman numerals?

Not today. The song page shows chord names above the lyrics, plus the key, tempo and time signature. The Roman numerals come from the converter on this page, which runs in your browser.

How does the converter pick the key when I leave it on Auto?

It tries all 24 major and minor keys and counts how many of your chords belong to each. The key with the most chords wins, and ties go to the key whose home chord comes first, then last. Relative keys such as C major and A minor share their chords, so the converter names the runner-up too. Treat the result as a suggestion and confirm it by ear.

What does borrowed mean next to a chord?

A chord is marked borrowed when it uses a note outside the scale of the key, such as Bb in C major, which is bVII. It is not an error: songs often borrow chords from the parallel key. It can also mean the key is wrong, so compare it with the key Auto suggests.

Why do some numerals have a flat or a sharp?

A flat or sharp in front means the chord root sits a semitone away from the scale step. In C major, bVII is Bb, a semitone below the B that the scale has. Minor keys follow the natural minor scale, so the F in A minor is VI, not bVI.

Is it free to use?

The converter is free and needs no account. Chord Detector also shows the key, BPM and time signature of a whole song plus the chords of the first 60 seconds without signing up, and a free account unlocks your first full song with lyrics. After that a $5 pack gives you 10 credits, one full song each, or Pro is $9.99 a month after a 7-day free trial.

What if the song changes key?

The converter reads one key at a time. For a song that modulates, split the chords where the key changes and convert each part with its own key, so the numerals match what you hear in each section.

Find the chord progression of your song

Paste a YouTube link or upload a file, then run the chords through the chord progression finder above to read them as Roman numerals. The first 60 seconds of chords are free and no card is needed.

Get the chords of a song See pricing

Detection is automatic. Check the chords by ear before you perform.