What would be the key of a song containing the chords: A Maj, D min, C Maj, F Maj, and Bb Maj?

If the song is in the key of D minor then the A chord should be minor which it obviously is not. And if it is in the key of F major, again the A chord should be minor. I am really confused to find the key of these chords.

  • 2
    Can you show us sheet music please? – Aric Aug 9 '17 at 9:42
  • Borrowing from parallel keys happens a lot in music. Here, the A major could be construed as borrowed from D major. Songs in D minor are far more likely to have A major than Am in them. – Tim Aug 9 '17 at 12:35
  • Borrowing dominant chords in particular is exceedingly common, especially when the next chord is a fourth above; this type of borrowing is called a secondary dominant. An explanation of what a secondary dominant is does not belong in a comment (nor would it fit), but you should know at least that a dominant chord on the third degree of a major scale is a secondary dominant to the sixth, which is very common. – Fugu Aug 9 '17 at 12:47
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    Isn't A major consider a chord in the key of D minor and not a borrowed chord? This seems to be part of the OP's confusion. – Michael Curtis Aug 9 '17 at 17:01

First, it is perfectly acceptable to have a major dominant chord in a minor key. This is because the third of the dominant is the leading note in the key, and in a minor key this can be both natural or raised.

Take this example in A minor, which shows both the G as natural and sharpened in the minor dominant (v) and major dominant (V):

Minor Scale Triads

In D minor, all of those chords would fit. The "A#" is actually Bb, which is chord VI in the scale.

  • I think this is a fine answer but this diagram is really strange to me. Why is it labelling the VII as "pre-dominant" (subdominant?) but calling the v dominant? In what way is the III's function analogous to the iv's or the iio's? This is also just a weird subset of chords since it is neither all of the available triads from the composite minor nor only the available triads from the natural minor. I don't know; I feel like I have a very strong understanding of the underlying material here and that diagram gave me pause. – Fugu Aug 9 '17 at 13:09
  • @Fugu a predominant chord is any chord which normally resolves to a dominant chord. The dominant function has the role of creating instability that requires the tonic for resolution. – Aric Aug 9 '17 at 13:15
  • I know what it is, I'm saying the diagram is wrong. – Fugu Aug 9 '17 at 13:16
  • @Fugu pre-dominant and sub-dominant mean two completely different things. The diagram is correct – Aric Aug 9 '17 at 13:16
  • I am familiar with the distinction between subdominant and predominant; I was attempting to make sense of the diagram. As is, it appears to indicate heirarchal harmonic function (TSD) but then throws in predominant out of nowhere. The diagram both seems to confuse subdominant and predominant and categorize chords that can't definitively be called either (like the III) predominant. – Fugu Aug 9 '17 at 13:36

Based solely on the chords, I'd hazard a guess that the song is in fact in D minor. Your assumption that "If the song is in the key of D minor then the A chord should be minor which is obviously not" is incorrect--the A (major) chord is found in D minor all the time.

The C and F chords also fit in D minor, and the "A sharp major" chord should really be spelled as B flat major--which still fits in D minor.


Probably D minor. But it could be F major. Or C major. What chord feels like 'home'? What chord does the piece end on?

Understand that the notes of a scale are the framework of a key, not a restriction. 'Outside' notes and chords are common. Think of it like a room, with an overall colour scheme of blue and grey. Nice! Stable and relaxing. But you can bring in a vase of red flowers. Even prettier. But you're still in the same room.


This chord progression is either in the key of D minor or the relative major of F major, depending on how the rest of things go.

Here's how I break it down. Personally, I'm inclined to look at this as being in F major (because it's my personal opinion that not too many things are actually written in the natural minor scale, but you're free to analyze it otherwise if you want to).

A7 Dmi C7 F Bb

That gives us...

V7-of-vi vi V7 I IV

A very standard progression. The use of the secondary dominant to the sixth is extremely common - you could almost consider V7-of-vi a second primary dominant because this relationship is so typical.

EDIT: This interpretation holds true even if you don't utilize the implied sevenths, as I did in my analysis above. Without the sevenths, you get this:

V-of-vi vi V I IV

Still effectively the same and really only different in the context of performance -- indeed, if I saw this progression written the way it is in the question, I would play the A major and C major as A7 and C7.

  • This won't be using the scale notes from D nat. min. The A chord sees to that. So it's probably using D harmonic minor notes, thus chords. Check your 1st line - Dm - relative major = F major!! – Tim Aug 9 '17 at 12:32
  • @Tim The presence of C(7) and Bb means that if you analyzed this in the context of minor you'd be analyzing it as natural minor with a substitution on the i or else you'd have to say that two chords were borrowed from outside the key and I'd really like to see the rationale for that because it'd definitely be twisted. – Fugu Aug 9 '17 at 12:39
  • Don't know where the dom 7th parts came from - not in the OP's question. I'm not analysing it with respect to anything but the 'minor'. That can, and does, come in several forms, thus the relative minor of F is simply Dm. It's not prescribed as any particular sort of minor - which occurs in the scales rather than the key. Yes, the natural minor (relative) contains exactly the same notes as its relative major, but that in itself has no bearing on this situation. Please don't forget your 1st line! – Tim Aug 9 '17 at 12:57
  • I labelled those chords as dominant 7ths to clarify their function since in the chord progression in the question those are dominant functioning chords. If you want to just play a major triad, that's fine; their function is the same. I'm not going to get into a pointless debate about whether the relative minor of F major is D natural or D composite minor; at the end of the day I'm going to analyze this in F because it resolves to F and functional relationships are a lot more intelligible in major keys. I only need to identify a secondary dominant to make this make sense in F. – Fugu Aug 9 '17 at 13:04
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    I was in fact using that simple system. No point in pursuing this further. Are you going to correct your first line? – Tim Aug 9 '17 at 13:35

D min, C Maj, F Maj, and Bb Maj are all in F major where we have all three primary chords I, IV, V, (F, Bb, C respectively.)

A Maj would be the odd chord out. If the key is F major, this chord could be V/vi which is a very common "secondary dominant."

You could also say the key is D minor. In this case the A major is the dominant in the key of D minor. But, if we are only looking at a list of chords, the absence of G minor makes it a little bit less convincing.

The typical way of resolving this question is to look at beginning and ending of the music where you usually see the music start in end in one key. Or, you might look to see if either D minor or F major get more emphasis to become the key center.

I'm implying that all three primary chords are needed to define a key, but that is not a necessity. It's just one way to try to make a judgement call about this list of chords.

In F: 
A = V/vi, 
Dm = vi, 
C = V, 
F = I, 
Bb = IV

In D minor: 
A = V, 
Dm = i, 
C = VII, 
F = III, 
Bb = VI

...containing the chords...

FWIW: I'm not considering this a 'progression' in the sense that it specifies the order the chords are played it. Also, I'm not assuming any one chord or group of chords is used more than the others.

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