The Elements of Harmony > Key (in-depth)


To describe the modulation from one key to another, we can adopt the following notation:

An L-shaped bracket indicates a modulation. Chords before the bracket belong to the

preceding key, while chords after the bracket belong to the new "target" key. Furthermore,
the target key is indicated to the right of the bracket, like this: .


In modulating from one key to the next, certain harmonic formulae must be invoked in
order to create a smooth transition. The following table, showing most modulations in
symbolic form, describes the harmonic procedures for modulating from a current to a
target key. Chords are notated using  Chord Type nomenclature, which is the simplest
to understand and visualize. See footnotes for further explanations.

     Modulation Procedures using Chord Type nomenclature

Current Key

I VIm  I -  ∟VIm       V7  - i    Note: It's best to use a commom chord before V7
I IV  I  - ∟IV          V7 - I    
I IVm  I  - ∟ IVm       V7 - i
I V  I  - ∟V        V7 - I        Note: It's best to use a commom chord before V7
I IIm  I  - ∟IIm        V7 - i
I IIIm  I  - ∟IIIm        V7 - i   Note: It's best to use a commom chord before V7
I II  I  -  V (common chord) - ∟II      V7  -  I

      I IV (common chord) - ∟bVII      V7 - I

or  I - ∟bVII     - iiø24** - V56 - I

I VIIm  I - iii (common chord) - ∟VIIm      V7 - i
I Vm  I - i (mode change) - ∟Vm       V7 - i
Im III  i - ∟bIII  V7 - I
Im IV  i - I (mode change) - ∟IV   V7 - I
Im IIm  i - V (common chord*) - ∟IIm    V7 - i
Im VIIm  i - ∟bVIIm   iiø24 - V56 - i
Im II  i - iv (common chord) - ∟bII      V7 - I
I III  I - viiº56** - bIII    viiº7** - I
I VI  I - ∟VIm   V7  -  i  - ∟VI   V7 - I
I Im  I - iiø7** - V∟I      i
Im I  i - iiø7** - V ∟I   - I
I III  I  - I I b7 ∟III    iiø3#4#6*** - I46 - V7 - I
I VI  I - ∟IVm   - V7 - I  - ∟bVI     V56 - I
I VII  I - V - ∟VII   iiø3#4#6*** - I46 - V7 - I

     I -  ∟IVm   V(V7) - VI - ∟bII   II - V- I

or I - ∟bV    V24 - I6 - ∟bII   V7 - I



      I -  ∟IVm V(V7) - VI - ∟bIIm   iiº - V- i

or  I - ∟#IVm    V24 - I6 - ∟#Im   V7 - i

I #IV orV  I - ∟#IV    V24 - I6 - ii7 (or ii56 or IV) - I46 - V7 - I
I IIIm  I - ∟bV   V24 - I6 ∟bIIIm   V7  - i
I #IVm  I - ∟#IVm   V24 - i6 - iiø7 (or iiø56 or iv) - i46 - V7 - i
I VIm  IV -∟VII  iiø3#4#6*** - I46 - V7 - IbVIm   V7  - i
I VIIm  I - bVIIm   iiø24** - V56 - i


                             * consider melodic minor scale of Target Key.

                             **consider harmonic major or harmonic minor scale of Current Key.

                             *** consider harmonic major scale of Target Key

How to interpret the nomenclature:

  • In the "Current" and "Target" columns, roman numerals denote the location on the major scale of the Tonic of each key, and the letter denotes whether the key is major or minor.

  • In the "Procedure" column, all roman numerals (shown in blue) represent triads in
    root position, and therefore indicate the function of the entire chord.
  • Uppercase roman numerals denote a triad with a major 3rd, while lowercase roman numerals denote a triad with a minor 3rd.
  • The remaining part of the chord symbol determines the presence or not of a 7th,
    possible alteration of the 5th  and possible inversion of the chord. The exact
    meaning of the symbols ø and º are described here, while the interpretation of
    the arabic numerals is described here.




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