Why do the same roman numerals give different chords in a minor key?

Because the scale they are stacked from is different. Taking every other note of a natural minor scale produces a different pattern of qualities from a major scale, so the first degree comes out minor and the third major. The numeral names the degree, and the quality follows from the key and the mode.

Can I build a progression starting with any chord?

Yes, the order is whatever you click. The numerals are shown so you can see what you have chosen, not to constrain the sequence, and any of the seven can come first, including the diminished chord if it is what you want.

Why is the result an arpeggio rather than block chords?

Playing one tone at a time makes each chord's notes audible in sequence, which is easier to judge than a wall of sound and gives a clear pulse to hear the tempo against. It is a rendering choice for clarity, not a statement about how the progression should be played.

What does the tempo change?

The length of each note and therefore the total duration. Each tone lasts an eighth note at the chosen tempo, so a faster tempo compresses the whole progression and a slower one spreads it out, without altering the chords themselves.

Can I add seventh chords to a progression?

Only the diatonic triads are offered here, since those are the seven that belong to the key without any added notes. A seventh chord can be worked out with the chord calculator, and its sound imagined from the triad the tool plays.

Chord Progression Builder

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Chord Progression Builder lists the seven chords that belong to a key and lets you click them into a progression, which it then renders as audio. The roman numerals update with the key and the mode.

What is Chord Progression Builder?

Choose a key and a mode, click the triads in the order you want them, and generate the progression as a WAV.

The controls and the display:

A key root with an octave, defaulting to C4.
A mode selector with major and natural minor.
A tempo from forty to two hundred and forty beats per minute, defaulting to ninety.
Seven buttons, one per degree of the scale, each showing its roman numeral, its root and its quality.
A line naming the selected chords in order and a readout of the chord count, the tempo and the resulting duration.

The seven chords come from the scale itself. Each degree of the scale is taken as a root and stacked in thirds using only notes from that scale, which produces a fixed pattern of qualities: in a major key the chords are major, minor, minor, major, major, minor and diminished, and in natural minor the pattern shifts so the first and fourth degrees are minor. Those patterns are why the roman numerals matter. A numbered progression describes a shape rather than a set of chords, so the same sequence moved to another key preserves its character, and the tool shows the numerals alongside the roots precisely so that the two can be read together. Roman numerals in upper case indicate major chords and lower case minor ones, and the diminished chord is marked as such, so the quality of each degree is legible at a glance rather than having to be worked out. Selecting is a toggle: clicking a triad adds it to the end of the progression, and clicking one already chosen removes it, so the order is the order you clicked in. The render plays the progression as an arpeggio rather than as block chords, one tone per eighth note at the chosen tempo, which makes the harmony easy to hear and gives a rhythm to judge the progression against.

What it does not do:

Triads only, so there are no seventh chords or extensions.
No inversions or voice leading between the chords.
Major and natural minor only, so the other modes are not offered.
No rhythm, melody or arrangement beyond an even eighth-note arpeggio.
Nothing is saved, so the progression exists only in the current page.
The render is a plain WAV without any instrument modelling.

Use it to hear how a progression in a key sounds before committing it to a song, to check the quality of the chords on each degree, or to practise over a sequence. When the scale behind those chords is the thing being studied, the scale generator spells it out, and when a chord needs its full spelling or a quality outside the seven diatonic triads, the chord calculator covers all fifteen of its forms. The selection order is the progression, so a sequence can be built up a chord at a time and then trimmed by clicking a chord out of it again, which makes auditioning alternatives quick. Since the pattern of qualities is fixed for a mode, the same numerals always give the same kind of progression in any key, which is the property that lets a shape be moved from one song to another without rewriting it.

How to use Chord Progression Builder

Set the key root and choose major or natural minor.
Click the triads in the order the progression should play.
Set the tempo and check the duration readout.
Generate and play the WAV to hear the progression as an arpeggio.

When to use Chord Progression Builder vs related tools

Chord Progression Builder is the tool when the question is which chords belong together in a key and how they sound in sequence. Chord Calculator spells any single chord and includes qualities outside the diatonic set, while Scale Generator shows the scale those chords are built from. When the relationship between keys rather than within one is the point, Circle of Fifths Tool maps the whole set.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.