Chord Progression Generator

Pick a key, scale, and progression pattern to generate the actual chords, roman numerals, scale notes, and chord tones using standard diatonic harmony.

Quick Facts

Method
Diatonic harmonization
Chords are built by stacking thirds (every other note of the scale) on each scale degree; the scale's interval pattern fixes whether each chord is major, minor, or diminished.
Major-key triad qualities
I, ii, iii, IV, V, vi, vii°
Uppercase numerals are major chords, lowercase are minor, and vii° is diminished — this pattern holds for every major key, just transposed to a new root.

Your Results

Calculated
Chord Progression
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Actual chords in your key
Roman Numerals
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Scale-degree pattern
Scale Notes
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Notes of the chosen key/scale
First Chord Tones
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Root, 3rd, 5th (stacked thirds)

Ready

Choose a key, scale, and progression pattern, then press Generate.

Understanding Diatonic Chord Progressions

This tool builds a chord progression the way traditional music theory does: it starts from a major or natural minor scale, stacks thirds on top of each scale degree to form a chord, and reads off the result as both a letter-named chord and a roman numeral. Enter a key, a scale, a progression pattern (a sequence of scale degrees like 1-5-6-4), and a chord type, and the calculator returns the actual chords for that progression.

The formula

A major scale follows the interval pattern whole-whole-half-whole-whole-whole-half (in semitones from the root: 0, 2, 4, 5, 7, 9, 11). A natural minor scale follows whole-half-whole-whole-half-whole-whole (0, 2, 3, 5, 7, 8, 10). Once the seven scale notes are known, each diatonic chord is built by stacking every other note starting on a given scale degree — the 1st, 3rd, and 5th notes counted from that degree for a triad, plus the 7th note for a four-note seventh chord.

  • Major scale triads: I, ii, iii, IV, V, vi, vii° — major, minor, minor, major, major, minor, diminished.
  • Natural minor triads: i, ii°, III, iv, v, VI, VII — minor, diminished, major, minor, minor, major, major.
  • Roman numeral case encodes chord quality: uppercase numerals are major (or dominant) chords, lowercase are minor, and a degree mark (°) denotes diminished.

Reading a progression

A progression pattern like 1-5-6-4 means "play the chord on the 1st scale degree, then the 5th, then the 6th, then the 4th." In C major that resolves to C, G, Am, F — one of the most recorded chord sequences in popular music. The same 1-5-6-4 pattern in A natural minor instead produces Am, Em, F, Dm, because the underlying scale — and therefore each chord's quality — changes.

Assumptions

The calculator assumes standard 12-tone equal temperament, strictly diatonic harmony (no borrowed chords, secondary dominants, or chromatic alterations), and spells every note using sharps rather than key-specific enharmonic spelling (so it shows D# rather than Eb). These are simplifications that keep the math transparent; a full arrangement may use different spellings or add chords borrowed from outside the scale.

Frequently Asked Questions

How does the calculator turn scale degrees into actual chords?
It builds the seven-note major or natural minor scale from your chosen key, then stacks every other note starting on each scale degree — the 1st, 3rd, and 5th scale tones for a triad (add the 7th for a seventh chord). The resulting interval pattern between those stacked notes determines whether the chord is major, minor, or diminished.
What do the roman numerals like ii, V, and vii° mean?
Roman numerals label a chord by which scale degree it's built on. Uppercase numerals (I, IV, V) are major or dominant chords, lowercase numerals (ii, iii, vi) are minor chords, and a small circle (vii°) marks a diminished chord. The same numeral pattern transposes to any key — I-IV-V is always the same shape, just built from a different root.
Why do the same scale-degree numbers produce different chords in major versus minor?
Major and natural minor scales have different interval patterns, so the same numbered scale degree lands on a different note and gets a different chord quality. The 1-5-6-4 pattern is C-G-Am-F in C major but Am-Em-F-Dm in A natural minor, because the underlying scale — and therefore every chord built from it — is different.
Does this include 7th chords, borrowed chords, or other extensions?
You can switch chord type to 7th chords, which adds the diatonic 7th on top of each triad (for example V becomes a dominant 7th, ii becomes a minor 7th). The generator sticks to strictly diatonic harmony, though — it does not add borrowed chords, secondary dominants, suspensions, or other chromatic alterations.

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