I have been doing chord analysis on BWV 846 (prelude). It is very interesting and I hope you can help me with some questions:

  1. I understand that doing chord analysis is good but what is the reason for doing it? Will really it help me become good at improvisation and writing songs?

  2. I found a website with a chord analysis of this prelude but I still have questions on the chords. the second chord is said to be Dmin/C. Shouldn't it be Dmin7/C?
    The sixth chord is said to be D7/C. Why is not written as D/C? The eighth chord is written as Cmaj/B but shouldn't it be written as CM7/B? In this piece there are also some diminished chords. How do you know what chord it is when some diminished chords have the exact notes? We also have a chord written as G7/sus4. I didn't even know sucha chord existed. Anyway, is it really fine to write baroque chord analysis using sus4? The twenty third chord is written as Abdim but that wrong. Is this even a chord at all? Now, what about the three last chords. The last is C but the other two is difficult to figure out. They are not written correctly on the website. Are they even simple chords?

  3. I understand that chords can be written in different ways but what is the right way to write them in chord analysis of baroque pieces?

Analysis from the site cited above:

BWV846 harmonic analysis

  • 8
    However you write the chords names, what you are doing is an anachronism, because that's not the way Bach thought about harmony. Read the (long) chapter on figured bass in CPE Bach's "True art of playing keyboard instruments" for example. I think analysing BWV846 as 5-part counterpoint is more interesting and instructive than trying to "name that chord". And for extra credit compare the voice-leading with Bach's 4-part chorale settings, imslp.org/wiki/…
    – user19146
    Jun 29, 2015 at 0:40
  • I'm not suggesting you try this at home, but if you want to get an idea of how a Baroque-era musician would have learned to create pieces like this prelude, see: faculty-web.at.northwestern.edu/music/gjerdingen/partimenti/… Jun 29, 2015 at 22:23
  • I agree with @alephzero. Most of those "slash" chords are best considered as suspensions in the bass, until you get roughly to the latter third of the piece, where you have a dominant pedal followed by a tonic pedal.
    – user16935
    Jun 30, 2015 at 5:38
  • Doing chord analysis for getting better at writing songs is good if you analyze Paul McCartney or Elton John. Not so much Bach. For one he does not use song structure, for another, as mentioned, chordal analysis is anachronistic/inappropriate for Bach. May 21, 2022 at 14:14
  • 1
    @VictorEijkhout Bach wrote a good number of songs; he just used different structures for them than 20th-century pop songwriters. But chordal analysis isn't entirely anachronistic or inappropriate. Bach may never have thought of roman numerals, but the theory of inversions that led to them originated with his contemporary, Jean-Philippe Rameau, and it is certainly a useful tool for analyzing Bach's music.
    – phoog
    May 22, 2022 at 17:13

6 Answers 6

  1. From my experience, seeing what other composers do, by analyzing their songs will help you with your music. I mean you can write a book, but if you read another book, you'll see what other authors are doing
  2. Dmin/C and Dmin7/C are pretty much the same. Technically, yes you have to mention the 7, but since the 7th is C and it's on the bass, it's shown on Dmin/C. D7/C and D/C are the same, like above. To be honest, since the analyst didn't include the 7th in the first example, it's inconsistent to do it here. The Major 7th chord can be symbolized both M7 and maj7.

You know what diminished a chord is, when you see what chord goes to the diminished one and where it leads to.

I don't think they used sus4 chords in Baroque music. Maybe it's delayed resolution. Ιf you notice, the C that is the 'sus4', is being played by the same voice on the previous beat and in the next it goes to B. That is the real note of the chord. Not sus4; that's wrong.

Yes, Ab dim is a correct chord.

The third from the end chord is F chord with the C on the bass. The notation is correct. The second from the end is G7, with the C as the bass. C isn't in the chord notes, but the composer is keeping it anyways. ( I don't remember the name in english exactly, will look it up). Τhis was pretty common in Bach's compositions.

  1. The way they are notated there is fine. Another thing you can do is that you can use roman numerals instead of the chord names. Like I, II7, V6-5 etc
  • Roman numerals are better than just something "you can use"; they are the most appropriate way to annotate a baroque score. I point this out because the questioner specifically asks "what is the right way to write them in chord analysis of baroque pieces?" Jul 4, 2015 at 12:56

To add what Shevliaskovic has posted it also aids in the speed of learning pieces. If you ever wanted to have an musical eidetic memory you can start to learn such a skill by becoming proficient in score analysis.

When you see one of the great pianist for instance play a long concert it sometimes look like they are staring into the distance while playing. The thing is they are not really staring at anything but rather seeing the score they learned from in there minds eye.

When your get adept at learning musical memory you can visualize the score in such detail as to remember little imperfections in the paper it was written on and even stains on the paper.

Some musicians even insist that they never see another score of music they have already learned because the moment they see a diferent picture of the music they know the conflicting pictures ruin the whole memory of the original score.

This is a very excellent skill to have but it all start with the painful process of learning to analyze scores quickly and well.


Baroque composers thought in terms of figured bass. To them the bass note was foundational and they thought of the structure above it in terms of the intervals of the notes from the bass. This was because they were trained in using and playing from a figured bass. Analyzing Bach by means of figured bass gets you inside the composer's mind better than any other way. If you don't know how to do this R O Morris's book "Figured Harmony at the Keyboard" is a good place to start.


In the last three measures, the composer is using a pedal tone (also called pedal point). This is something Baroque composers loved to do at the end of a piece: hold a bass note for several measures while the harmony changes above it.

  • Actually, the pedal points start in m.24. There are two: a dominant pedal point from m.24 to m.31, and a tonic pedal from m.32 to the end.
    – user16935
    Jul 4, 2015 at 14:32

I offer my answers as a professor of music at a university, PhD in musicology.

  1. You need to make a distinction between descriptive analysis and 'true' analysis. Sure, labelling chords i.e. describing the harmonic structures, will do little for you. On the contrary, asking how and why will be extremely informative. Here are some questions for you to ask yourself:
    What is the purpose of the first four chords, I ii V I? Why doesn't it go anywhere?
    Then what chords are used to make the progression actually get somewhere?
    Why is the II-V in bars 3-4 in different inversions to the same chords in bars 5-6?
    What effect does it have if you put them in root position like bars 5-6?
    What is chord X doing and what is it's relationship to the tonic?
    Is there really any modulation?
    Why the dominant pedal at the end?
    Why are those chords above the pedal those particular chords?

    So who cares right? If you don't know which chords do what and all their variations and substitutes, then your tool kit will be pretty limited. Will help with improv? Absolutely. If you understand how harmony moves music forward, keeps it static and makes it cyclic, then all you need to do is choose the chord that achieves whatever it is you need. Sure, some random, inexplicable chromatic chord can be inserted but why? For effect, for colour.
  2. In bar 6, the analyst has labelled the diminished as a G diminished - this is incorrect. The chord here is built on C-sharp. The chord here is not diatonic and therefore exhibits secondary function, i.e. it is not the leading tone (vii) diminished chord of C major, but of what key? Of D minor. How do we know? Look at what happens around it. G is not the leading tone chord of D minor but of A-flat major. If the ensuing chord was A-flat, then without any doubt whatsoever, Bach would have spelled the diminished chord G, B-flat, D-flat, and F-flat. It's all about function. An understanding of function will allow you see the ingenuity of each composer - the types of chords they use to fufil a purpose; how they subvert function, modify it, substitute it, disguise it, destroy it completely. Etc...

All the chords underpinned by the dominant pedal serve to prolong the dominant - to increase the tension creating a greater need for resolution. All of those chords there are, in function, the dominant, G.The analyst labelled a chord in bar 14 as 'Adim/G' - this is incorrect. This chord is an F-sharp diminished seventh (over a G bass) i.e. the leading tone chord of the dominant, G. Another question to ask, why introduce the diminished seventh there?
I hope that's some help!

...That's the short answer...

  • There is no F# on bar 14. Jun 4, 2022 at 14:03
  • 1
    @MichaelBaudin there is in the image shown in the question, which uses a half measure for each measure of the original. The F sharp, therefore, is in bar 28 of the original.
    – phoog
    Jun 22, 2022 at 12:07

Here is a beginning of how I understand the chords:

              [C key]     [G key]
1      C      I
       Dm     ii
2      G7     V
       C      I
3      Am     vi      =   ii
       D7                 V
4      G                  I
       C                  IV
5      Am                 ii
       D7                 V
6      G                  I

After bar 7 it gets more complex, feel free to continue (and post your analysis too).

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