Chord progressions
Pick a key and its seven degrees appear, ready to play. Stack a progression, hear it, send it to the editor. Or load a song from the catalogue to see what each of its chords is doing.
Key
Click a chord to add it to your progression. Click its diagram to hear it on its own.
Your progression
Click chords above to build a progression.
A song from the catalogue
Load a song to see each of its chords numbered in the key you chose.
Degrees, or why these chords belong together
A key is not a list of chords to memorise, it is a role given to each one. The first degree is rest, the fifth is the tension that pulls back to it, the fourth is the step away that lets the music breathe. Those roles do not change when the key changes: only the names do. That is what roman numerals write down, and it is why a musician who thinks in degrees transposes without thinking about it.
| Degree | C major | A minor |
|---|---|---|
| I / i | C | Am |
| ii / ii° | Dm | Bdim |
| iii / III | Em | C |
| IV / iv | F | Dm |
| V / V | G | E |
| vi / VI | Am | F |
| vii° / VII | Bdim | G |
C major and A minor hold exactly the same chords: all that changes is the note you come to rest on. That is the first thing this tool lets you try, switching between the two modes without losing your progression.
Borrowed chords
A borrowed chord is taken from the parallel mode: a minor fourth degree inside a major key, a flattened seventh, a lowered sixth. It sounds foreign without actually leaving the key, which is exactly what it is there for.
They are far more common than people assume. The bVII opens whole choruses in rock and pop, and the minor fourth degree is the melancholy colour above all others, the one that darkens a cadence without breaking it.
Secondary dominants
A secondary dominant treats one degree of the key as if it were a tonic of its own, for the length of a single chord. In C major, an A seventh is not a disguised sixth degree: it is the dominant of the second, and it announces the D minor that follows.
This is the mechanism that makes a simple progression feel like it travels without ever changing key. The tool shows all of them, each with the degree it points at.
What this tool does not do
- It does not guess your key, it asks you to choose it. The reason is measured: on a four-chord loop, automatic detection never exceeds fifteen per cent confidence and picks the relative minor half the time. Am F C G reads just as well as i-VI-III-VII in A minor and as vi-IV-I-V in C, and both readings are correct.
- It does not track key changes inside a song. Across the public catalogue, only seven charts genuinely leave their key: far too few to build anything on, and a wrong detection would cost more than it would give.
- It does not write music for you. It shows what exists and why it holds together; what comes next is yours.
- It does not know about inversions or extensions beyond the root. A C over E is numbered as a C.