Roman Numeral Notation Of Chords
- Yash
- Jun 7, 2022
- 5 min read
You have learnt about all the notes that exist in western music. You know all the chords there are. B Major, C Minor, E Diminished... There is no song that you can't learn now, no chord progression you can't improvise over. So you go to your favorite band's audition and they ask you to solo over a "ii-V-I" progression.
You stand there dumbfounded and realize that the only reason letters were able to invade mathematics is because the numbers were off invading music.
Today we are going to take a look at what these roman notations mean in music.
You need to know what are scale degrees and diatonic chords in order to understand this topic.
What is numeric notation of chords, and why do we need it?
In any scale, every note has a chord built on it, using it as the root. The C Major scale has diatonic chords C, Dm, Em, F, G, Am, Bdim.
Every major scale, starting on all the 12 notes in an octave, has the same order of chords. The first chord of the scale is major, second is minor, and so on. (The full order is M m m M M m dim)
So if all major scales have the same order of chords, we can find a way to generalize the chord names instead of remembering all the scales separately.
Generalizing this means that if you have prepared a song in one key but want to play it in another key for a different singer, you can just play the same numbered chord in the new key. For example, 4th chord in key of C is F, and the 4th chord in the key of E is A. So you can easily, and quickly, figure out a chord progression in any key as long as you know the numerical notation of the chord.
How does roman notation work
A roman numeral notation of a chord tells you three things: What degree of the scale that chord is built on, whether that scale degree is natural or altered (♭ or ♯), and whether it's a major chord or a minor chord.
If the chord is built on the 1st degree of the scale, it will be the 1st chord. Therefore, we will use roman notation for 1, which is "i" or "I". If the chord is major, we will use "I", and if it is minor, we use "i".
If the chord is built on the 2nd degree of the scale, we will use "II" or "ii".
For now, this is what we need. I will explain about the third thing that this notation tells us later on in this article.
Diatonic chords of the major scale
As always, we talk about the major scale first, since that is considered the "default" scale. All the scale degrees in a major scale are natural or perfect, so we don't have to worry about the degrees being flat or sharp.
The chords of major scale in order are 1- M, 2- m, 3- m, 4- M, 5- M, 6- m, 7- dim.
Using the information we learnt about roman notation, we can see that the first chord would be "I". Second chord would be "ii". Third would be "iii", and so on.
The seventh chord is diminished, and the way to write it is to use the lower case letters and the sign for diminished chord after it, which is "°" (The degree sign). Therefore, the seventh chord becomes vii°.
All the diatonic chords of Major scale are: I, ii, iii, IV, V, vi, vii°.
Now you don't need to worry about remembering any chord progression of major scale in every possible key. You just need to remember the numerical order and it can be applied on any key.
For example, the "I - IV - vi - V" progression becomes "C - F - Am - G" in the key of C Major, and "B♭ - E♭ - Gm - F" in the key of B♭ Major.
Showing scale degrees in roman notation (Using minor scale)
We saw that when we write "vi", it means that we played a minor chord starting from the 6th degree of the scale. But there lies the problem. The 6th degree of the major scale is a major 6th, while the 6th degree of the minor scale is a minor 6th. So we need a way to specify that too.
We do so by writing flat or sharp before writing the roman numbers, like ♭VI or ♯IV. For example, let's take the minor scale. The scale degrees are: 1, 2, ♭3, 4, 5, ♭6, ♭7
The diatonic chords of a minor scale are: m, dim, M, m, m, M, M.
Consider the 3rd chord in this scale. It is built on the 3rd degree, so it will be either "III" or "iii". Since it is a major chord, it will be capitalized, so "III". However, the 3rd degree itself is a flat 3rd (or minor 3rd), so the actual notation would become ♭III.
Can you guess how you would write the 6th chord in minor scale?
Since it is built on 6th degree, and a major chord, it will be VI. However, the 6th degree in a minor scale is a ♭6 interval, so the chord becomes ♭VI
Using this process for all the scale degrees, we get the diatonic chords of the minor scale:
i, ii°, bIII, iv, v, bVI, bVII.
If You know what are modes, you can try doing this process for all the modes of the major scale too. Check if you got them correct by reading this article on Modes and their diatonic chords.
Roman notation for all triads
There are several triads. Major, minor, diminished, augmented, suspended.
Here's how you write all of them using roman notation:
Major- Upper case roman numerals. Eg. I, II, ♭III, ♯IV
Minor- Lower case roman numerals. Eg. i, ♭ii, ♯iv
Diminished- Lower case numerals with the "°" sign. Eg. ii°, ♯iv°, vii°
Augmented- Upper case numerals followed by "+" or "Aug". Eg. III+, ♭II Aug, ♭VII+
Suspended- Upper case numerals followed by Sus. Eg. IVsus2, ♭IIIsus4, ♯IVsus4
Roman notation for 7th chords
If you already know about 7th chords, you are probably well above the level of the target demographic for this article, but here's a brief anyway.
There are many types of 7th chords but those are a topic for separate article. Here are the ones you will encounter the most:
Major 7: Upper case with "Maj7", "𝅈7" or "M7". Eg. IIMaj7, ♯IV Maj7, VI𝅈7, ♭VII M7
Minor 7: Lower case with "min7", "m7" or "-7". Eg. ii m7, ♭vi-7, vii min7
Dominant 7: Upper case with "7". Eg. V7, II7
Half Diminished 7: Lower case with "ø". Eg. iiø, ♭viiø
Full Diminished 7: Lower case with "°7". Eg. vii°7, ♯iv°7
Quiz for your practice
What is the 6th chord of a minor scale, written in roman notation?
♭VI
What is the 7th chord of a major scale?
vii°
What does ♭iii° mean?
A diminished chord starting on the ♭3 degree.
What is the ♯IV+ chord if the scale is starting on C?
This is an augmented chord starting on the ♯4 scale degree. ♯4 from C is F♯.
So it will be F♯ Aug.
What is the ♭VII chord if the scale is starting on E♭.
This is a Major chord starting on the ♭7 degree. ♭7 from E♭ is D♭. So, the answer is D♭ Major.
Conclusion
In this article, we learnt about the basics of roman notation.
Capitalized letters are used for major (and augmented) chords and lower case letters for minor (and diminished) chords
The roman number tells you what scale degree the chord is built on.
The accidental (♭ or ♯) tells you the nature of the scale degree being used.
There will be a few chords that you might encounter that look like V7/ii. These are advanced concepts that I will cover in separate articles. Keep an eye out for them in the future by subscribing to my blog.
Thankyou for reading. Hope this helps you.
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