On reading my new theory book I have come across a very interesting passage on Keys Change.

Here are the rules:

When the music changes keys, it changes to a closely related key

Closest related key is the relative minor

The other close keys to modulate to are next to the original key on the key circle

Other modulation could include the parallel, Maj C to Min C.

Source: Music Theory 101, Brian Boone and Marc Schonburn

I am not disputing this, and it makes sense especially when you look at the circle of keys but would changing to a different key completely be such a bad thing? I must admit, sadly I am not at the stage where I can 'hear' music like you guys can (or even read it all that well as a matter of fact), but would modulating to a key that's not either of the above be a bad move?

We hear of great composers, Sibelius, Nielsen, Stravinsky and Elgar who frequently composed symphonies (and other works) that were so incomprehensible, no set way of playing something, flexible, stormy, tempo not settled, melodies and harmonies abandoned and so on. Could one way to do this be to change the key to something that broke the rules or is this vital rule implemented for a reason my book has not disclosed?

  • 14
    Don't expect "Music Theory 101" to apply to real works by real composers. It only applies to what it says on the cover: Music Theory 101. It's like applying "Physics 101" to driving a car.
    – fdreger
    Commented May 4, 2020 at 18:53
  • @fdreger longing to find a book that applies real works by real composers :(
    – cmp
    Commented May 4, 2020 at 19:10
  • 1
    Do you want ideas and patterns for composing? Check out Mel Torme's Christmas Song, it has a brief modulation from C major to E major. It doesn't stay there for long though. So, the "rule" has exceptions ... It might be more useful for your studying to look at example cases and then try to replicate the same patterns in your own compositions. Pat Metheny's song books are good source material for finding different modulation patterns. Commented May 4, 2020 at 19:15
  • 1
    @cml: nothing will just "apply". You need theory 101, then theory 201, then 301 and maybe 401, and then a lot of experience that is really hard to put into words and sometimes is only reachable through metaphors. It's exactly the same as using theory of literature to analyze works of real writers.
    – fdreger
    Commented May 4, 2020 at 21:06
  • This is probably to get the beginner a feel for common, easy to digest, key changes. In fact you can modulate form any key to any other key any way you like. I would recommend reading Modulations by Max Reger for more.
    – user50691
    Commented May 4, 2020 at 21:31

6 Answers 6


WARNING: This got a bit out of control. Please don't be intimidated by the diagrams and the wall of text. Also please note that in the following (and in the music, generally) the word "modulation" means just a change of key.

Obviously, these modulations are the most common ones. However, you can modulate from any key to any other key without much hassle. The only thing you need to do is to find a path between the two keys. (There are many, many possible paths between any two keys, so it's your choice. It can be shorter or longer, whatever you like.)

The book talks about the modulations in the terms of the circle of fifths, which is, in my opinion, a great approach, so I'll stick to it in this post.

As your book correctly notes, the safest modulation is to the neighboring keys or to the relative minor/major keys. So for now, the possible paths look like this (see the left circle): Two circles of fifths, the left has arrows from C major and a minor to the neighboring keys, and an arrow between them. The right also has arrows from a minor to E major and from f minor to C major. I drew the paths only for one key (C major), but it works just the same way for all 11 other keys. (The drawing would also get messy very fast.)

Another, very common and useful way of modulating, is using the dominant seventh chord in the minor keys (for instance, Ami - E7). This makes it possible to modulate up by 4 sharps very fast. I drew the paths that use this in blue on the right image.

However, we can extend this logic as far as we want. Basically: whenever we find two chords that sound well one after another, we can use them to modulate. The only thing we need to do is to "hammer it home" after modulating, so there is no doubt that we really are in the new key.

So say that we would like to modulate from C major to E major. One possible path would be going through A minor. So we play chords: C -- Ami -- E. But with this, the modulation is not yet done (in fact, if we stopped with E, it would look like we ended in A minor and that E was used to "hammer the A minor key home"). We need to play something that will firmly root us in E major, and that needs to be some chord that 1) pulls strongly to the E major chord, and 2) is not contained in A minor, so that it's really clear we're not in A minor anymore. A good choice would be B7 (with its D# and F#, it makes it very clear it does not belong in A minor). So we would play something like: C -- Ami -- E -- B7 -- and now we are in E major, so we can continue with anything from that key, for instance F#mi -- G#mi -- A -- B -- E. We're just firmly there.

But this mechanism can be used for any transition. So let's say we found out that playing Ab major after a C major sounds good. We can immediately use it to modulate: C -- Ab -- Eb7 -- Ab and we're there. We can also target other chords than the tonic: so if I wanted to go from Bb major to G major, I can do Bb -- Eb -- D (here we ended up at the dominant of the target G major) -- G. (Or Bb -- Gmi -- D7 -- G. Or anything.) If you can play the guitar (or any other instrument capable of harmonies), I think you should try these simple progressions out.

And now, there are lots of chord pairs that sound good. We can, for instance, use the idea of secondary dominants: we can prepend any chord from our key by its own dominant chord and it will just sound good. So we can "embellish" the progression C -- G to C -- D -- G (D major is a dominant to G, and it works out in spite of the fact that it does not belong into C major.) Or we can play: Emi -- F#7 -- B7 instead of just Emi -- B7.

So let's draw that into our diagram (with magenta arrows, see the left circle below). And while we are at it, we can also use modal progressions (for instance a minor to D major, making it sound like the Dorian mode, or C major to Bb major, which sounds like the Mixolydian mode, etc. -- green arrows). Or we can use the simple modulation to the minor/major key of the same name (using the dominant chord, for instance C -- G7 -- Cmi; goldish arrows). Or we can use any trick we can think of (some of my favorite are shown in orange arrows -- also note that sometimes you can make up two or more reasons for drawing a single arrow between two keys!). More circle of fifths with more confusing arrows.

The diagram is pretty confusing by now, but it illustrates my point: you can easily go from anywhere to anywhere just in a couple of steps. And all of them can be made pretty smoothly, so don't think that half of those arrows corresponds to some cringeworthy modulations that are maybe possible in theory but ugly in practice. It's exactly the other way around: there are many more possible ways to make beautiful modulations, but drawing the arrows wouldn't really serve more purpose :--). And mind you, the same set of arrows is going from each of the other 11 minor and major keys.

And these are only the possibilities of modulating "by harmony". You can also modulate with melody only. It's also possible to use a modulating sequence (a simple lick that sounds well if followed with its own transposed copy), or a device that I would call "chromatic mess", essentially starting to use weird chords that do not evoke any particular key (like the diminished 7ths, or maybe some quartal/quintal harmonies), chaining them chromatically, and emerging in a totally different key. Really, the sky is the limit here!

  • I know you feared this would be difficult to understand, but I found it very clear. The final circle covered with colored lines illustrates well that there are many more ways to modulate than one could fit on the circle. Nice answer, thanks for taking the time to write it. Commented May 5, 2020 at 19:16
  • And this doesn't even touch on the "trucker's key change"! Commented May 5, 2020 at 19:55
  • @chrylis-onstrike-, it doesn't, because I don't know what that is! :--) (If I had to guess, would it be moving up/down a semitone?)
    – Ramillies
    Commented May 5, 2020 at 19:57
  • 1
    @Ramillies It is, or even up two semitones, but with no subtleties whatsoever, i.e. you simply end one chorus in C and then start another in D.
    – Jos
    Commented May 6, 2020 at 10:15
  • Ah so. I know this under the name of "pop modulation" :--).
    – Ramillies
    Commented May 6, 2020 at 13:33

I wouldn't say this is a "rule" so much as a guideline for the most common modulations. Most theory textbooks have something called "closely-related keys" or a similar term. They generally include (1) the relative major/minor, (2) keys within one sharp or flat (including their relative majors/minors), and (3) the parallel major or minor. That's the same list you quoted there.

This is by no means a "rule." It's just a list of keys that are relatively easily accessible through basic modulations by common chords and such. It's quite easy to modulate to more "distantly related" keys too. It is just generally accomplished by different, more "advanced" techniques (e.g., common-tone modulation, enharmonic modulation or reinterpretation, tritone substitution, etc.).

I'd also note there's a kind of historical bias to these guidelines. Originally, instruments were not necessarily equally tempered. That is to say, some keys were more "in-tune" than others. Many historical instruments were designed to play in specific keys or closely related ones, and notes outside those keys were more difficult to execute and/or increasingly out-of-tune. Thus, the concept of "closely-related keys" was important historically, as in some cases it defined limits on reasonable modulations that could still be performed well and relatively in-tune.

However, with the gradual push toward equal temperament that occurred from roughly 1700 to 1900, all keys on most instruments became roughly playable. So abrupt modulations connecting far-away keys also become more reasonable and occurred more frequently. Still, introductory theory textbooks generally begin with "closely-related key" modulations, as they are the most frequently encountered and often the easiest to accomplish convincingly in beginner exercises.


I'd put those 'key changes' quoted more as modulations. Moving, in some cases so subtly that some listeners might be unaware - and also retaining the facility to return, subtly again, to the original key.

They missed the two most common key changes in moders music - upa one semitone, and up one tone. Neither of which, particularly the former, leaves a simple and mussical way to return.

We really have to find a more exact word that 'rules' for these sort of questions. 'What has been found to work already' springs to mind, but it hardly trips off the tongue, let alone the fingertips! And the penalties for breaking these 'rules' - progress! If we all stuck religiosly to those 'rules', music would stagnate. Rant over!

Basically, use those 'rules' as and when you feel the need, but why not try out other ways and targets to change key? And, as I said in an earlier question, all the fuss is over within two bars, maximum, by which time the listener is involved in the new key, and cannot continue to be in the old key, mentally, physically, or musically.

The theory book quoted has started at the beginning, with basics. It's the start of the journey, and hasn't gone far. Bit like, when you were three, you couldn't take 5 away from 2. Good enough at that time?

  • Rules in music have been developed of the practice - if not a real Pope has postulated some rules.
  • There have always been music popes - theorists - which have their disciples and followers and composers - practitioners - who were founder of a new theory with their own community and their own school.
  • Modulation is referring to the term mode - and a change of mode was historically changing within modes of a common scale.
  • It makes sense that a theory book is oriented on the historical development of harmony (as-well as melody and counterpoint).

  • The history of music is an endless story of the wrestling of tradition and revolution.

Btw: There are many harmony books treating modulation with examples of original works of great composers.

Just as example: The most recent I’ve found are the books by Percy Goetschius!


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Here are some pages of the book:

The theory and practice of tone-relations : a condensed course of harmony conducted upon a contrapuntal basis


  • Yes! I have found an actual PDF. Thanks so very much. I can already tell this will be a good read :))))))))))
    – cmp
    Commented May 4, 2020 at 20:22
  • Wow, that actually looks like a really good book!
    – Ramillies
    Commented May 4, 2020 at 20:33
  • @Ramillies if you google Percy Goetschius there’s a good PDF result for the whole book!!!
    – cmp
    Commented May 4, 2020 at 20:38

The term for a changing of key is 'Modulation'.

The truth is you can modulate to any diatonic step in the scale.

You would modulate to the type of chord the scale degree has, let me explain what I exactly mean by that.

If we take C major as an example

Modulation to the 2nd note.

You can modulate to the second step (called the Super Tonic). So the key of D, the super tonic chord in a major key is a minor chord so if your parent key is C major and you modulate to the super tonic, you go to d minor.

You can modulate to the 3rd note

You can modulate to the third step (called the Mediant). So a key starting on E in this example. The mediant chord in major keys is a minor chord so if your parent key is C major and you are modulating to the mediant you are heading towards e minor.

You can modulate to the 4th note

You can modulate to the 4th note (called the Sub Dominant) So a key starting of F if our parent key is C. The 4 chord in a major key is a Major chord so in this instance we would go the F major if we modulate to the Sub Dominant

You can modulate to the 5th note

You can modulate to the 5th note (called the Dominant) So a key starting of G if our parent key is C. The 5 chord in a major key is a Major chord so in this instance we would go the G major if we modulate to the Dominant

You can modulate to the 6th note

You can modulate to the 6th note (called the Sub Mediant) So a key starting of A if our parent key is C. The 6 chord in a major key is a minor chord so in this instance we would go the a minor if we modulate to the Sub Mediant

You can modulate to the 7th note

You can modulate to the 7th note (called the Leading Tone) So a key starting of B if our parent key is C. The 7 chord in a major key is a diminished chord, but the minor third in that chord tells us we should be going to b minor if our parent key is C major and we are modulating to the Leading Tone key

off course you can go to parallel keys and the relative keys

There is off course modulations that are easier to make convincing than others, but all these in this answer is possible and if you go along the theory path long enough you will learn to do them all.

  • There are many more modulations than these. And to change key often means to go from major to another tonic major, as in from C maj. to D maj. Key C going to B minor sounds quite unconvincing - you use the leading note to be the tonic of a key. It really isn't.
    – Tim
    Commented May 6, 2020 at 11:52
  • The second line statement just isn't true. Pieces modulate up a semitone as much as anywhere else. Say from E to F. F isn't diatonic in E, so there's a misleading statement.
    – Tim
    Commented May 8, 2020 at 12:36

As Max Reger brilliantly demonstrated, there isn’t really any rule. You may go from any tonic region to any other directly, just knowing how to voicing the changes. The “rules” we encounter all over the web are more stylistic and didactic than practical. For example, in Mozart’s time, the style employed banned too much tensions and modulations to far related keys. His famous quartet dubbed “Dissonances” is highly dissonant for his contemporaries, but not dissonant at all, not to all styles that came after.

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