It shows the pull
Every degree sits according to its function — tonic, subdominant, dominant — and lines of varying weight show where it leads. The weight is the real frequency.
ChordGravityMusic theory, measured
You don't pick a chord. It pulls you.
Play a chord and ChordGravity shows where the harmony wants to go next, and how strongly. Not from a textbook, but from counting 47,848 real chord moves — from Palestrina's polyphony to two hundred rock songs.
Open the explorerFree, no account, everything runs in your browser.
Three things this tool does
It names what you write
Play V then I: perfect cadence. V then vi: interrupted cadence. VII then i: Aeolian cadence, the one behind minor-key rock and a great deal of film music.
It lets you take it away
Playback in four styles, in 4/4 or 3/4, then MIDI and MusicXML export with tempo, note lengths and voice leading intact.
The same cadence is not worth the same in every period
This is the heart of what ChordGravity measures. Each cell gives how often a chord move occurs in that repertoire, in major keys.
| Palestrina | Monteverdi | Bach | Mozart & Haydn | Rock | |
|---|---|---|---|---|---|
| V → I | 50 % | 41 % | 67 % | 53 % | 62 % |
| IV → I | 35 % | 31 % | 27 % | 51 % | 68 % |
| I → IV | 26 % | 26 % | 23 % | 17 % | 47 % |
| ♭VII → I | 15 % | 17 % | 12 % | — | 57 % |
“—” marks a move too rare to display. Figures match the application, up to rounding.
Rock and Bach agree about the perfect cadence and part company on everything else. The plagal axis is what makes the song: IV→I reaches 68% in rock against 27% in Bach. Where the chorale uses the subdominant as a run-up to the dominant, rock makes it a round trip that needs nothing further. And ♭VII→I, at 57% in rock, barely exists in the classical repertoire.
Five repertoires gone through chord by chord
| Repertoire | Period | Pieces | Chord moves |
|---|---|---|---|
| Palestrina | v. 1570 | 80 | 6,024 |
| Monteverdi | v. 1600 | 49 | 3,916 |
| Bach | v. 1730 | 433 | 18,584 |
| Mozart & Haydn | 1770-1790 | 25 | 2,801 |
| Rock | 1955-1999 | 200 | 16,523 |
47,848 chord moves in total
How the figures are obtained
The four early repertoires are analysed from the music21 corpus: each piece is reduced one vertical sonority at a time, a key is estimated per bar, every chord is reduced to a scale degree, and ornamental sonorities are set aside.
The rock corpus is of a different kind: its degrees and keys are written by musicologists, chord by chord. It is the most reliable of the five.
A degree only shows a percentage past twenty occurrences. Below that, the app says so rather than inventing a figure.
Frequently asked questions
Is ChordGravity free?
The explorer is entirely free: all twenty-four keys, the five repertoires, playback and cadence recognition. Only file export is intended to become paid.
Do I need to install anything?
No. Everything runs in the browser, including the sound synthesis. No account is required and nothing is sent to a server.
Where do the percentages come from?
From counting five corpora: Bach's chorales, masses by Palestrina, madrigals by Monteverdi, quartets by Mozart and Haydn, and two hundred rock songs analysed by Trevor de Clercq and David Temperley. No value is written by hand.
Are these figures rules to follow?
No, they are observed frequencies. A rare chord move is not a wrong one — often the reverse. Knowing you are leaving the slope beats believing there isn't one.
Why no jazz?
The available collections of standards note a single key for a whole tune, whereas jazz changes key by the bar. Figures drawn from that would look right without being right.
Can I export to my music software?
Yes, as MIDI and MusicXML, with tempo, metre, note lengths and voice leading. Both exports are unlocked in the current version.