What are roman numerals chords and how are they used in piano chord progressions? Learn more about chords and how to understand these chord markings.
Do you know how the use of the Roman numerals for chords works? The Roman numerals represent each step in a scale, either major or minor.
From each step of the scale a triad or a basic chord in root position can be built:
The chord on the first step will then be called I, on the fourth IV, and the fifth V, and so on. The I, IV and V chords in any major or minor scale are the most important. They are the main chords of the scale.
Why not use regular Arabic numbers?
Since there are a lot of other numbers involved when playing chords, for example the "number label" for seventh chords (7); so to avoid confusion, roman numerals are used instead to represent steps on the scale, as well as the chord built on that step.
This also makes it easy to “translate” every piano chord progression to any scale you want. You just need to know the scale you want to use, and then find each chord from the steps in that particular scale.
And why not only use “regular” chord markings, like Gm7? (=G minor with a seventh)
Well, those tell you to play in a specific tonality- while the roman numerals chords make it easy to play chords from any scale.
Another number that might be added is V7, this means that the chord on the fifth step (V) of the scale is “colored” with a seventh.
All the major scales will have the following chords build on each step up:
I - ii - iii - IV - V - vi - vii° and back to I (or VIII)
The little circle ° means that the chord is diminished. Translated to a C major scale the chords are:
C – Dm – Em – F – G – Am – B dim, and back to C
Any natural minor scale will have these chords:
i - vii° - III - iv - v - VI - VII - (i)
Translated to an A minor scale the chords are:
Am – B dim. – C – Dm – Em – F – G - Am
Here is a good resource about chord progressions: Basic Chord Progressions, Handy Guide (Amazon)