Based on my understanding of chord theory, the chords used in most modern popular songs are comprised of notes that occur in the scale of the tonic key for that song. The I, ii, iii, IV, V, vi, and diminished 7th chords in any major key, will (to the best of my knowledge) be comprised of notes from said scale.

But in the key of G major, the Fmaj chord is often used in the chord progression. Yet the root note of the F major triad (F) does not appear in the G major scale.

And it's not just G major this happens in. I see songs in D with the C chord in them, songs in A with the G chord, songs in E with the D chord. In all of these instances, the seemingly out of place chord appears to be a major chord derived from a root note which would normally be the 7th degree of the scale - but lowered a half step.

How is this reconciled with the general idea that the chords used in a song, usually consists of notes available from the scale of the tonic key for that song? And why does it seem to work so well?

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    This is in fact one more question about modal interchange. See this and this answer for a short explanation of this important concept.
    – Matt L.
    Commented Feb 13, 2015 at 21:23
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    'Based on my understanding of chord theory, the chords used in most modern popular songs are comprised of notes that occur in the scale of the tonic key for that song. ' Therefore your understanding is wrong. As you state, many songs use bVII. And other chromatic chords. They don't need special justification.
    – Laurence
    Commented Oct 10, 2017 at 10:34
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    You are using 'textbook' traditional western conventions. But that's not where most modern popular music comes from: In blues, jazz and most rock music, the dominant 7th chord - bVII - derived from Mixolydian mode - is the default 7th chord and considered consonant - 'diatonic' in a manner of speaking.
    – Stinkfoot
    Commented Nov 22, 2017 at 19:33
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    your question would be more precise if you did tell us where you noticed this change of chords. I suppose it is in the bar leading to the refrain or in the 2nd last bar. look up my answer. Commented Jan 11, 2019 at 15:44
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    @AlbrechtHügli Where in the song is pretty irrelevant to OP's question. OP notices a trend that these chords exist and asks for an explanation. Your answer does mention it, but OP does not need to clarify the question.
    – user45266
    Commented Jan 11, 2019 at 16:54

12 Answers 12


I would argue that your premise that the chords used in a song should be comprised of notes that occur in the scale of the tonic key doesn't really hold. Yes, the majority of songs tend to use almost exclusively diatonic triads, however, there are many example of non-diatonic chords, for instance, borrowed chords and secondary dominants.

In traditional analysis, the bVII in a major key is considered to be a borrowed chord, meaning that it is borrowed from the parallel minor, or another parallel mode.

A possibly more useful (albeit unconventional) way to think about this is that this chord is acting as sort of a IV of IV chord. A typical chord progression with bVII looks something like this: I, bVII, IV, I. In C major, for instance, that would be C B♭ F C. B♭ is IV in F and F is IV in C, so there is some symmetry to this sequence, which is what makes it sound so natural. In addition, the lowered 7th sort of "pulls" downward to the 6th scale degree (the third of the IV chord), making the progression from VII to IV feel very natural and satisfying.

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    Another place it could be borrowed from is the Mixolydian mode which also has a Major chord built off the tonic and fits in perfectly whit your sample progression.
    – Dom
    Commented Feb 13, 2015 at 19:30
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    If the topic is modern popular songs, is it statistically true that "The majority of songs tend to use almost exclusively diatonic triads" ? From casual observation it seems that unadulterated major tonality is not such a common beast in pop music these days. Commented Feb 14, 2015 at 9:24
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    Yes the vast majority of pop songs are still harmonically driven by some sequence of I, IV, V, and vi (or i, III, VI, and VII) with other chords occasionally mixed in (often V/vi). There are a fair amount songs that use a borrowed bVII or a V/V (II) in their primary progression, but these songs are still in the minority.
    – Casey Rule
    Commented Feb 14, 2015 at 15:23
  • Just recently encountered it in the Elton John song "Yellow Brick Road"
    – acjay
    Commented Mar 16 at 2:20

On a basic level, this is just a modal chord progression using the Mixolydian mode, which contains a b7 scale degree. That makes the notes you're using G A B C D E F G. The G major triad (G B D) and the F major triad (F A C) are both right in there. But doesn't necessarily reconcile other chords aside from those two (assuming not all the songs you're talking about only have two chords). If a song in G has an F major (bVII) chord, but also has a B minor (iii) or D major (V), then those chords are not all coming from Mixolydian, as the Bm and D both F#s in them. Those scale degrees would instead harmonize as a B diminished (iiio) and a D minor (v) in Mixolydian.

In these cases, the progression is actually a modulation between Ionian (the major scale) and Mixolydian. The basic tonality will be that of a major scale, using the typical chords, until the F major chord is hit. Then you switch to hearing Mixo. Your ear will still pull to G and hear it as home, but that chord rings out and it really does have a neat sound.

I think my favorite example of this modulation is Elton John's 'Bennie and the Jets'. The G to F progression is a big tag in the song. However, the chords aren't just triads. They're both major sevenths. So that's G B D F# and F A C E, respectively. You see both the F# and the F there. The Gmaj7 implies Ionian (G A B D E F# G) while the Fmaj7 implies Mixolydian (G A B D E F G). Such a small difference, but a really smooth sound.

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    @Jef See the end of Matt L.'s answer above where he explains why he says "As a final note, modal interchange is usually not viewed as modulation for two reasons: ..." But I suppose you could refer to it as temporary modulation - as in for one measure that the bVII chord is used. But I wouldn't I don't think. Commented Feb 14, 2015 at 16:16
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    @Dan Davis Thanks for your input. Interesting examples. But the songs I refer to just include the bIV chord as part of the progression (say one measure each verse) and I don't think they modulate between modes. One song example starts on G then goes to D, Em, F, C, D and back to G to start the progression over. Leading into the chorus it repeats the F, C, D pattern a few times. I think that song might actually modulate to C major in the end where it uses a G, Bb, C progression (using Bb as the bVII of C). But it does appear that bVII is often used as a substitute for vii dim. Commented Feb 14, 2015 at 16:34
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    I wasn't quite sure of the technical term, but the concept should be the same. And in that particular example, the D chord would contain an F#, so there is that difference. And it looks like I need to read more about modal interchange. Great question.
    – Dan D
    Commented Feb 14, 2015 at 17:43
  • @DanDavis you know, I have been thinking about this and I am beginning to wonder if the song I illustrated may in fact modulate to C and back again. I wonder if a song can modulate for two chords over two measures and then back. Quite possible that Bennie and the Jets is modulating back and forth as well. I might write a new question to cover this modulation question in it's own right. Commented Feb 14, 2015 at 22:38
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    There is no such thing as a modulation from one mode to another based on the same tonic. That's just mixing modes.
    – user9480
    Commented Feb 15, 2015 at 3:03

There are already some good answers, but I'd like to add an important term for a concept which is able to explain really a lot of occurrences of non-diatonic chords in popular music (and not only there). The concept is called modal interchange [1], which is the borrowing of chords from parallel tonalities. The borrowing of chords from the parallel minor key has been mentioned in Casey Rule's answers, but modal interchange is more general in the sense that it includes the use of chords and chord scales from any scale/mode with the same root.

Indeed, one common form of modal interchange is the borrowing of chords from the parallel natural minor scale, which results in the following additional chords:

Im7 II-7(b5) bIIImaj7 IVm7 Vm7 bVImaj7 bVII7

Especially the last five chords (bIIImaj7 up to bVII7) are used extensively in pop tunes written in a major key. The use of chords from the parallel natural minor in a major key adds some dark or bluesy color to the typical major sound.

Note that other modes, such as lydian, dorian and phrygian are also used for modal interchange, even though they are found more often in jazz than in pop or rock music.

Also note that in a major key, the bVII(maj7) and the Vm7 are most easily explained by modal interchange from mixolydian, because only the 7th scale degree needs to be lowered to obtain these two chords, no other scale modification is necessary. This was correctly pointed out in a comment by Dom.

As a final note, modal interchange is usually not viewed as modulation for two reasons:

  1. the tonal reference remains the same
  2. the borrowed chords are usually only interspersed in the progression, so the focus does not change from one key/mode to another (as is the case with modulation), but both modes co-exist.

[1] B. Nettles, R. Graf, The Chord Scale Theory & Jazz Harmony


To supplement the previous answers, I would say that the diminished vii° chord formed from the notes of the major scale is unsatisfactory for many musical styles due to its dissonance (it has a tritone instead of a perfect fifth). When a consonant triad on the seventh degree is wanted, the easiest solution is to chromatically lower the root of the chord. Because the third and fifth are still in the key, the chord is relatively unobtrusive.

This trick has long been practiced on the ii° chord of minor keys, yielding a bII or "Neapolitan sixth" chord. bVII in major did not really come into vogue until the 20th century (though isolated occurrences can be found in Brahms and others). It often progresses to IV, demonstrating its "IV of IV" function; it also often progresses to V (as in the songs "Try to Remember" and "All I Ask of You"), taking over the principal function of the old Neapolitan sixth.

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    Interesting way to look at modal interchange, but I don't think that it aligns very well with the actual mechanisms of songwriting and composition. Composers don't usually think "hmm, I want to write a chord on the seventh degree" and then decide to chromatically alter it because of the diminished quality. Composers don't give the scale degree of the root anywhere near that level of importance (well, they do, but they weight that heavily with the functional and harmonic properties of the resultant chord on that root) when writing music.
    – user45266
    Commented Mar 10, 2020 at 18:35
  • Yes. ♭VII is not a sub for vii♭5. If they would want to work around the vii♭5's dissonance, they would either put it in first inversion or transform it into a diminished seventh chord.
    – user71438
    Commented Aug 16, 2020 at 5:29

Why does it seem to work so well?

The ♭VII major chord has a strong harmonic relationship to the tonic. Within the first few harmonics (with most instruments) there are overtones that approximately correspond to the lowered seventh and the second degrees of the tonic scale, which are the first and third of the ♭VII chord:

1st harmonic = fundamental tone
2nd harmonic = octave
6th harmonic = fifth above 2nd octave
7th harmonic = minor seventh above 2nd octave

8th harmonic = 3rd octave
9th harmonic = whole tone above 3rd octave

And the fifth of the ♭VII major is the fourth above the tonic, so there's a relationship there too.

How is this reconciled with the general idea that the chords used in a song, usually consists of notes available from the scale of the tonic key for that song?

Firstly, why would it be necessary to reconcile it with that idea? A song with a major tonic chord is not necessarily in in the major key in the sense of adhering to the diatonic major scale. For one thing, it may be in the mixolydian mode (as another answer explains). But what if there's a major V chord, ruling out the mixolydian scale?

If we need, (and again as explained well in other answers) there are ways you can reconcile it with the idea that the song using diatonic harmony in a major key. For one, you could consider that the song is modulating. The only problem with that is that modulation implies a change in the tonal centre, and many songs with ♭VII don't really give that feeling.

Another idea you could use is the idea that the ♭VII chord is 'borrowed'. There's a problem with that too, though - if our chord progression is a typical 3- or 4- chord sequence going round and round (e.g. The Who's Can't Explain, our 'borrowed' ♭VII doesn't really sound 'out of place' any more than the other chords.

It's arguably simpler to just say that a lot of very simple music does not stick to diatonic scales. And why should it? There are harmonic correlations to be exploited all over the 12 tone equal-temperament scale outside the bounds of using 7 notes diatonically.

Playing a note a tone lower than the tonic is a very natural thing to do if you're from a blues guitar background, as it's right there in the blues scale, and if sounded along with the tonic it will sound less nasty with distorion than the semitone lower. And if you're playing the note, why not prop up a major chord on it too? There's no reason not to.

I think part of the problem is with beginners' theory books that are slightly too tilted towards trying to see everything as basically major or minor (or modal if you've read to the end). As yet another answer said, there's a big world out there.


Casey and Dan's answers are great. To add to Casey's, the F leads nicely to Em. In Roman numerals, this would be bVII -> vi. Pink Floyd uses this progression on Dark Side of the Moon, in the song Breathe (and maybe another song on that album as well). When used well, non-diatonic chords really do amazing things to music!


As Casey Rule points out, bVII of a major key might be used as IV of IV.

bVII might also be used before a perfect cadence V I. In this case you could analyse the bVII and V together as being basically V7. Here, bVII is a substitute chord for V7. V7 contains the 2nd and 4th degrees of the scale; these are kept, and instead of the rest of V7 the flattened 7th degree is substituted, to complete a triad. The 7th degree is flattened because, otherwise, the triad would be diminished.


This a an excellent question, Rockin' Cowboy. If you can wrap your head around these ideas, it will help you to understand most Western music. These 'rules' should not be thought of as rules, but descriptions of common practice. (I took two years of music theory at my local community college, my teacher was a concert pianist, and a fantastic musician and teacher.)

When we say that a piece of music is in C major, what we mean is that C major is the most prominent key of the piece. Most pieces start and end in the same key, but often modulate to other keys.

Here are the most common ways in which music modulates to other keys.

Modulation to 'closely related keys'. This means to a key with one sharp or flat difference in the key signature. In practice, this means that the tonic (the note with the key is named after) shifts up, or down, a fifth. That is five scale tones. So, in the Key of C major (no sharps or flats), the two closely related keys are G major (one #) and F major (one b). c,d,e,f,g (up five scale tones) c,b,a,g,f (down five scale tones). In the key of F, Bb is the IV chord. So, this is one way in which an Bb could occur in a piece of music in the key of C major. (or in the key of G major, and F major chord, the IV chord in the key of C major, a closely related key in G) Note: Taking away a sharp is the same as adding a flat, and taking away a flat is the same as adding a sharp. Example: If we are in 3 flats and we add a sharp, we are now in 2 flats.

Additionally, if we are in C major (no sharps or flats) we could modulate to 1#, but instead of going to G major, we could go to e minor. Or 1b, to d minor.

Another common modulation is to the relative minor. That is, the minor key with the same key signature. The relative minor of C major is 'a' minor. (the convention is to capitalize the note name of a major key, and use small cases for minor keys) in a minor key, a major V chord is used. In 'a' minor, the V chord is an E major chord. In the key of C, you will commonly find that an E major chord is used, usually followed by an a minor chord. If an e minor chord is used in 'a' minor, this is called the mode of 'a' minor, the KEY of 'a' minor uses an E major chord. The chord based on the fifth scale degree is called the 'Dominant chord'. That would be G or G7 in the key of C major, or the key of c minor. A g minor chord in the mode of c minor. The tonic of the relative minor key is 6th scale degree of the relative major key. The tonic of the relative major key is the 3rd scale degree of the relative minor key.

Another common modulation is to the 'Parallel Minor'. That is a minor key that has the same tonic as the Major key. In C major, the parallel minor is c minor.

Here, we need to explain how chords are formed, this is commonly called 'stacking thirds', that is skipping every other note in the key. For example, if we stack thirds in the key of C major, starting on the tonic, we get the notes, c, e, g. This is the tonic, a C major chord, containing the 1st(tonic), the third, and the fifth notes in the C major scale. If we want to make 7th chords, we use for notes; c, e, g, b, creating a C maj7 chord. The tonic chord is denoted with a Roman numeral I. In a minor key, the tonic is denoted with a small case Roman numeral i.

If we 'stack thirds' staring on the 2nd note of the C major scale, we get; d, f, a, an d minor chord, designated by the Roman numeral ii, lower case because it is minor.

All major keys follow this pattern, I ii iii IV V vi viio(diminished)

All minor keys follow this pattern, i ii(dim) III iv V VI VII

Notice that the VII chord in c minor is Bb major. I we are in G major, an F chord could be borrowed from g minor, the VII chord of g minor.

There is also the concept of 'Secondary Dominants'. The most common secondary dominant is the dominant of the dominant. In C major, the Dominant is a G major chord. The dominant of the dominant, denoted V/V is a D major chord. You will often find music in the key of C will have a D major chord (not in the Key of C major, C major has a minor ii chord i.e. d minor) followed by a G major chord i.e. V/V V.

Secondary dominants in the key of C major are:

V/ii - Amaj or A7, usually followed by dm V/iii B7 - em V/IV C7 - F (common) Note that C7 does not occur in the key of C, but the key of F. V/V Dmaj - Gmaj V/vi Emaj - am V/viio Fmaj - b dim (same as IV viio) Note: vii0 has same function( dominant function) as the V chord.

Another common modulation is to the relative major of the parrellel minor. For example; if we are in C major, the parallel minor is c minor, it's relative major is Eb major.

Or, we can modulate to the parallel major of the relative minor. In C major, relative minor is 'a' minor, parallel major is A major.

If we are in a minor key, the relative minor of the parallel major. For example: If we are in c minor, the relative major is C major, it's relative minor is 'a' minor.

Or, to the parallel minor of the relative major, in c minor, there relative major is Eb major, the parallel minor; eb minor.

There is also something called the 'Protestant Bump'. This is usually done in a major key, we simply modulate up a half-step or a whole-step. That is, for example from C major to Db major or D major.

Here is another explanation for your example; an Fmaj chord occurring in the key of G. This is not uncommon in rock or country music. A song may be in the key of G, but use the I,IV and V chords from the key of C i.e. G,F, and C. One might analyze this as mixolydian mode harmonized I ii iiidim IV v vi VII. Note that these are the same chords that occur in C major, but the numbers have changed.

In C major: C, dm, em, F, G, am b dim. In G mixo: G, am, b dim, C, dm, em, F

There is one more very important idea that modern musicians must take into account. That is the influence of the blues. A blues progression throws out the 'rules' discussed above (with the exception of the last idea, the mixolydian harmonization) and uses an entirely different basis.

A blues progression uses Dominant 7 chords for the I, IV and V chords i.e. I7, IV7, V7. These chords are often played over with the same minor blue scale. Or the same major blues scale, or a both at the same time, sometimes referred to as mixo-dorian, or scales with the same tonic as the root of the chord being played over.

This pretty much sums up the music theory of harmony and modulation (non-jazz).


The other answers are best. But do also make sure you've actually got the key of the song correct. (I mention that just because people often learn the rule "songs have chord progressions comprised of notes from the scale of the song's key" at about the same time as rules like "songs have chord progressions beginning and ending on the root", or "songs have melodies beginning and ending on the root". Those rules are often broken too--and I've seen people misidentify the key as a result.)

  • Thanks Bruce. As a songwriter I am well aware that the first chord in the progression is often not an indicator of the key. But your are right, I find many folks just assume that if the 1st chord is a G the song is in G which is true about 70% of the time (wild guess). I find that a more reliable first glance indicator is the chord the song ends on (assuming it stays in the same key throughout). Most songwriters and listeners want the song to end up at home and resolve to the home chord. Unless the songwriter intentionally wants the listener to be left feeling unsatisfied. Commented Feb 15, 2015 at 16:05
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    Right, didn't necessarily think this was your mistake, but it seemed worth documenting for posterity. (Didn't notice TTas had already said something similar till now, oops.) Commented Feb 15, 2015 at 19:45
  • That's cool. TTas did mention it but he also said "Theory rots your mind and halts any progression" which has garnered him nothing but downvotes. I did not down vote b/c I know what he is trying to say, but his choice of words on a site about Music Theory is obviously going to ruffle a few feathers. So not as many people will see TTas answer and even if they did - the down votes will discredit anything he says. So plus 1 for documenting for posterity. Commented Feb 15, 2015 at 19:52

There are some situations where the bVII in pop music often appears:

a) at the 1. end of a phrase (half ending) before the repetition. (here it is substitution of the V7)

b) in the bar before the refrain leading to the subdominant: as a (IV - V) that means a secondary (IV - V)/ IV to the subdominant passage (often substituted by (IIm - V7)/IV

c) in the ending bars following as bVI - bVII from the minor mediante. e.g. lady madonna (Beatles) also called „Billy Chears“ progression (Sgt. Pepper album).

How would you describe F G A chord progression?

Is there a name for this cadence? (bVI bVII I)

WHY? This answer explains the harmonic reasons - but the effect is one of surprise ...


I agree with the other commentators who said it is a Mixolydian harmony (or better, chords built on a mixolydian scale)- I would like to add that in western music (american, english, and so on) you often hear this kind of progressions because they come from English Folk music of the past centuries, and this scale has got ancient origins (like most scales that we use in modern times)- I would also suggest reading the work of american etno-musicologist Alan Lomax, it is really interesting


Probably because the song is actually in the key of C maj. Just because a song starts with a certain chord doesn't always mean that is the key. Apart from this, there are many reasons for putting Gmaj with Fmaj. Best not to think about it too hard and just rely on time and experience to guide you. Learn as many songs as you can and you'll start to see the patterns without the need for a "musical theory". Theory rots your mind and halts any progression.

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    No I am not talking about songs in Cmaj (I'm not the one who down voted your answer BTW). I am referring to a multitude of songs that are squarely in the key of G that contain an F chord - it's quite common. You are correct in stating the widely known fact that the chord a song starts with does not always indicate the key. And I agree that a knowledge of music theory can potentially stifle some forms of creativity if you allow it to prevent you from thinking outside the box. But in many ways it can further your progression as a musician or in my case as a song writer/composer. Commented Feb 13, 2015 at 23:53
  • This is actually on the right track. But no, THE SONG is not in C, it has temporarily modulated there; see Dan Davies excellent answer above. G mixolydian == C Ionian...
    – Jef
    Commented Feb 14, 2015 at 6:33
  • I find the downvotes on this answer perplexing. If you were notating a song containing F major and G major chords isn't one way to cope with that to have a key signature of C major, even if C is not the tonal centre of the piece? Commented Feb 14, 2015 at 9:34
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    @topomorto Being in the key of C major means C is perceived as a tonic. If C is not the tonic then it's not C major even if the harmony matches. This is where the concept of modes comes in. It's like saying words that contain the same letters are the same word.
    – Dom
    Commented Feb 14, 2015 at 9:48

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