• Who Else Wants To Understand These Key Relationships? (Part 1)

    in Piano,Theory

    key relationships

    Once you put the concept of key relationships within your grasp, you’ll have an incredibly better understanding of how music works.

    Listening to jazz many years ago and trying to analyze the chords was a difficult feat. This was because although the chord changes were fantastic, I couldn’t fathom the relationship between them.

    Those were the days when a chord movement in the key of C, from the C major sixth chord:

    …to the F minor ninth chord:

    …would get me wondering why chord 4 (the F minor 9) included Eb and Ab tones:

    …despite them not being part of the C major scale.

    After I got familiar with several key relationships, the reverse became the case. I was able to analyze and properly explain the relationship between the chord changes. Story of my life!

    In this post, we’ll be covering three basic key relationships that can help you understand how all keys are related: enharmonic keys, parallel keys, and relative keys.

    Enharmonic Keys

    The term enharmonic is a word that represents the relationship between notes (two or more) that are spelled differently but occupy the same finger key on the piano.

    The notes C#:

    …and Db:

    …even though they are spelled differently, occupy the same finger key on the keyboard and, as such, are referred to as enharmonic notes.

    Therefore, the spellings “C#” and “Db” are also referred to as the enharmonic spelling of a particular finger key on the piano.

    Keys that are related by this enharmonic relationship are known as enharmonic keys. For instance, the major scale in the keys of C# and Db are practically going to utilize the same set of seven notes on the piano, but with different letter name spelling.

    While the C# major scale:

    …is spelled C# D# E# F# G# A# B# C#, the Db major scale:

    …is spelled Db Eb F Gb Ab Bb C Db.

    Here’s some of the major differences between the keys of C# and Db…

    The third tone of the C# major scale is E#:

    …while the third tone of the Db major scale is F:

    E# and F are two different spellings entirely. However, considering that both notes sound alike, it is possible for you to play some C# chords while in the key of Db. This is called enharmonic relationship.


    In the key of Db major, where the Gb major triad is chord 4, it’s possible to use a C# dominant seventh chord:

    …as a passing chord to the Gb major triad:

    “What is the relationship between C# dominant seventh and Gb major triad?”

    Although there’s no C# tone:

    …in the Db major scale:

    The C# dominant seventh chord is chord 1 in the key of C# major, and it has an enharmonic relationship with the key of Db major.

    (Note: Realize that most would reference and spell this chord in the key of Db as a Db7. However, there are much more practical places in the key of Db where you might want to use tones from the C# major scale. Think about the b6 tone (flatted 6). Would you rather explain to someone that you’re playing a Bbb diminished 7 (B double flat diminished seventh) or simply reference it as an A diminished 7? Believe it or not, this passing chord is very popular on the b6 degree and most would take the easier enharmonic spelling for simplicity’s sake.)

    Parallel Keys

    In music, there are two key centers (aka – “tonalities“) – the major key and the minor key.

    C major vs C minor:

    Db major vs Db minor:

    D major vs D minor:

    Eb major vs Eb minor:

    E major vs E minor:

    …and so on and so forth.

    There are 24 keys in music (if you do the math), considering that every finger key (aka – “pitch class“) on the keyboard has its major and minor key.

    There is a parallel relationship between a major key and minor key that share the same tonic (first tone of the scale). For example, the C major scale:

    …and the C minor scale:

    …are two two different scales, however, they are said to be in parallel relationship because the first tone (aka – “tonic”) of both scales is C.

    Remember that parallel lines never meet…

    The C major and minor keys are two parallel lines that never meet.

    While the C major scale consists of all white notes from C to C:

    …the C minor scale:

    …consists of three flats:

    • Bb
    • Eb
    • Ab

    To recap, this is a parallel relationship between major and minor keys that share the same tonic.


    If you understand these parallel relationships, it becomes easier to borrow chords. For instance, while in the key of C major you can borrow chords from the key of C minor.

    If you want to learn more about this, then you need to check out this post on the art of borrowing chords.

    A chord progression in the key of C major from C major sixth:

    …to F minor ninth:

    …is one typical example.

    Obviously, the F minor ninth is not one of the scale degree chords in the key of C major. However, it is borrowed as chord 4 from C minor (the parallel key.)

    Relative Keys

    Relative keys are keys that have the same key signature.

    Key signature simply means the numbers of sharps and flats a key has that distinguishes it from other keys. G major for instance, is the only major key that has one sharp (F#).
    Check it out below:

    Therefore, it is easy to know that we are in the key of G major if there is only one sharp – and that’s F#.

    But the key signature of key G major is identical to that of E minor, which is an entirely different key.

    The key of E minor also has one sharp (F#):

    …and that’s its key signature.

    So the relationship between keys that have the same key signature, a major key and minor key, creates a relative key relationship.

    Check out the scales of the keys of G major and E minor…

    G major scale:

    E minor scale:

    In each of the scales, you can see they consist of all white notes, except for F#.

    Attention: Although it’s possible for a major and minor key to have the same key signature, no two major or minor keys can have the same key signature. This relative relationship between G major and E minor is unique to them.

    “How do I know the minor key that has the same key signature as a major key, and vice versa?”

    Let me show you an effective way of finding out the minor key that is relative to any major key that you’re in.

    The minor key that is three half steps below any given major key is its relative minor key. Three half steps below C major is A, therefore A minor is the relative minor key of C major.

    Three half steps below E is C#, therefore C# minor is the relative minor key of the key of E major.

    Here are the relative keys:

    C major vs A minor

    Db major vs Bb minor

    D major vs B minor

    Eb major vs C minor

    E major vs C# minor

    F major vs D minor

    F# major vs D# minor

    G major vs E minor

    Ab major vs F minor

    A major vs F# minor

    Bb major vs G minor

    B major vs G# minor

    Alternatively, you can depend on the music clock (circle of fifths):


    …to help you determine relative keys.

    Here’s how it works…

    The inner sectors are the relative minor keys while the outer sectors are the major keys.

    Final Words

    While listening to the music of the masters, you’ll hear advanced chord substitutions and reharmonizations that are based pretty much on the principle of these relationships.

    Suggested reading: Subsidiary chords.

    In another post, I’ll be taking you a step further into key relationships by exploring closely-related and distantly-related keys.

    Until then.

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    Onyemachi "Onye" Chuku (aka - "Dr. Pokey") is a Nigerian musicologist, pianist, and author. Inspired by his role model (Jermaine Griggs) who has become his mentor, what he started off as teaching musicians in his Aba-Nigeria neighborhood in April 2005 eventually morphed into an international career that has helped hundreds of thousands of musicians all around the world. Onye lives in Dubai and is currently the Head of Education at HearandPlay Music Group and the music consultant of the Gospel Music Training Center, all in California, USA.

    Attention: To learn more about this, I recommend our 500+ page course: The "Official Guide To Piano Playing." Click here for more information.


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