Roman Numeral Analysis

Understanding Roman Numerals

When analyzing music, Roman Numerals have traditionally been used to represent chords build from each scale degree in a key. The roman numeral is altered to show both the quality of chord and the inversion of the chord.

The quality of the chord is shown by whether the roman numeral is capitalized or not and whether it has an additional quality symbol attached.

Diminished = [lower case]^o - ex: vii^o
minor = [lower case], for example: ii
Major = [upper case], for example: I
Augmented = [upper case]⁺, for example: III⁺

Notice that the quality symbols for diminished and augmented are the same as those used for chord symbols.

The roman numeral corresponds to the scale degree of the root of the chord. So, for instance, the I chord in C major is a C major chord, the ii chord is a D minor chord, etc. The roman numeral is normally placed below the staff.

To review Scale Degrees see Scale Degrees.

For a review of triads see Triad Types.

Diatonic Chords in Major

Diatonic chords are chords in which all of the notes belong in the key. In major there is only one type of diatonic triad built on each scale degree. In other words, if you build a diatonic triad using the same scale degree as the root, you will always end up with the same quality of chord no matter what key. The types of chords in major are listed below:

I ii iii IV V vi vii^o

Notice there are:

3 major chords: I, IV, and V,
3 minor chords: ii, iii, and vi,
and one diminished chord: vii^o.
There are no diatonic augmented chords in major.

Declaring the Key

At the beginning of any piece of music you are analyzing with roman numerals you will need to first declare the key of the piece. You do this by stating the key name followed by a colon. You will also need to do this any time the key changes.

Below are each of the triads and their roman numeral analysis in the key of C major.

  C:     I    ii    iii    IV    V    vi    vii^o

Below is a more complex example using a Grand Staff.

                    

       D:   I   IV   ii   V    vi 

To review identifying chords in actual music see How to Identify Triads in Actual Music.

Memorize This!

If you memorize the quality of the chord built on each scale degree, then you will no longer need to figure out the quality of a chord as long as it has no accidentals. Once you determine the Roman Numeral for the chord, you will automatically know the quality of the chord!

How to Identify Chords Using Roman Numerals

          

         

Identify the Key. To idenfity the key, you will need to know your key signatures. For now, all of our Roman Numeral exercises will be in major keys. In the example above, the key signature tells us we are in the key of Eb major.
Identify the Root of the Chord. Stack the chord in thirds to find the root of the chord. In the example above the notes stack in 3rds to form a chord with a Bb root.
        
Identify the Scale Degree of the Root. Count up from the tonic of the scale to determine the scale degree number. In the above example, the tonic note (scale degree 1) is Eb. If we count up from Eb we find that Bb is scale degree 5 or the Dominant. Eb = 1, F = 2, G = 3, Ab = 4, and Bb = 5.
Identify the Quality of the Chord. Place the correct Roman Numeral as listed in the Diatonic Chords above. When we check our list of Diatonic Chords in Major we see that the chord build on the fifth scale degree is always major. Therefore the correct Roman Numeral is V.