Chord progression finder
Drop a track and get the progression as Roman numerals as well as chord names, so you can see the shape of the song rather than just its notes.
Why Roman numerals
Chord names tell you what to play. Roman numerals tell you what the song is doing. Written as numerals, a progression stops being tied to a key: I-V-vi-IV is the same shape whether the song is in C or in E, which is why it transfers between songs and why you start recognising it once you have seen it written this way a few times.
The numerals here are worked out from the detected key. Upper case is major, lower case is minor, and a chord that does not belong to the key is shown with a flat or sharp sign in front of its degree.
Reading the shape of a song
Most popular music reuses a small set of progressions. I-V-vi-IV, vi-IV-I-V and I-IV-V turn up constantly, and once the timeline is in numerals you tend to spot the repeat before you have finished reading it.
Chords that sit outside the key are worth attention rather than suspicion. A bVII in a major key or a V in a minor key is a deliberate move by the writer, and it is often the most interesting bar in the song.
Questions
- What if the detected key is wrong?
- Then the numerals are shifted with it, since they are relative to that key. Check the key against the chord the sections resolve to; if it is off, the chord names on the timeline are still correct.
- Does it name the progression?
- It shows the numerals rather than labelling them. Once a progression is in numerals it is usually faster to recognise it yourself than to trust a label.