8 The Keys to Diatonic Chords – Guitar Theory


The Keys to Diatonic Chords

In This Chapter

  • Discovering diatonic chords
  • Charting out the diatonic chords for any key
  • Making educated guesses in terms of chord changes
  • Converting diatonic chords to generic terms
  • Understanding transposing

You’ve probably noticed by now that when you play songs on guitar, certain chords almost always seemed to be there with other certain chords. How often have you played a G chord in a song without there also being a C or D chord, or both?

You’ve probably also noticed that some guitarists and other musicians seem to be able to anticipate chord changes very well. It’s not just when a chord will change, but also which chord will be played next, almost as if the guitarist had written the song in question.

Both of these situations, and many others, can be explained by diatonic chords, which are chords that typically pop up in association with any one specific Major Scale or any one specific key signature. Understanding how diatonic chords are formed will help give you an edge when it comes to playing songs for the first time by helping you anticipate the likely chord changes throughout the song. It’s not foolproof—nothing is in music. But you’re likely to be right more often than not.

Turning the Major Scale into Seven Diatonic Triads

When you know the key or key signature of a song (and they are not always the same!), you can also make a very educated guess about the chords that will be used in that particular song. The chords used in many songs are often diatonic to the key or key signature of the song. And usually most of the chords are, too, which makes learning about diatonic chords even more helpful.


Diatonic chords are chords formed with the notes of a single Major Scale. For example, in the key of C major, whose scale is C, D, E, F, G, A, and B, F major (with the notes F, A, and C) and Em (with notes E, G, and B) would be diatonic to that key. D major (whose notes are D, F, and A) would not, since F is not a note of the C Major Scale.

Figuring out the diatonic chords of any key is easy, but the coolest aspect of them is that once you figure them out for any single major key signature, the pattern will hold for all major keys.

Charting Out Diatonic Chords in Any Key

What’s even cooler is that you already know the steps involved, from your interval work in Chapters 5 and 6. We’ll use C major once again as an example. Write out the seven notes of the C Major Scale across the top of a piece of paper. Then write them out again in a vertical column at the left of the page, like this:

The top line is strictly for reference. What you want to do is look at each note of the left hand column as a root note that you will be adding thirds. The thirds can be either major or minor but they have to be notes of the C Major Scale. So next write out “E” and “G” beside the “C” in the vertical column since in the C Major Scale E is the third of C and G is the third of E. Then add a note to remind you that those three notes form the C Major chord:

The next note in the vertical column is “D,” which is the second degree of the C Major Scale. Think of D as your new root note and then add the next third and fifth up from D, using just the notes of the C Major Scale. Your worksheet should now look like this:

Continue with this process, using each note of the left hand column as a new root until you get to B to finish the chart.

As you fill out the triads for each note in the left hand column, use the top horizontal line to remember your C Major Scale. When you want notes beyond B, as in the line starting with F in the left hand column, you simply start with C again. Your chart of diatonic triads should end up looking like this:

The Pattern of Diatonic Chords

Now examine the triads you’ve written out, which is a great way to reinforce what you learned about basic chord construction in Chapter 6, by the way.

The notes D, F, and A make up a D Minor chord, because F is a minor third (one and a half steps) higher than D and A is D’s perfect fifth. Both the triads beginning with “E” and “A” are also minor chords while those starting with “F” and “G” are major chords.

The triad of B, D, and F is a diminished chord, since D is a minor third up from B and F is the diminished fifth (the tritone, which is three whole steps higher).

When you have finished your chart, it should look like this:

We’re going to do one more thing, and that’s to add a list of numbers to the left of the left hand column. But not just any numbers, because we’d like to have some way of differentiating between the major and minor diatonic chord triads we’ve written out. Roman numerals work well in this situation because we can use uppercase for major chords and lowercase for both the minor chords and the lone diminished chord. Here’s the finished product:

Because the Major Scale is a set pattern, this pattern of diatonic chords will also be a set pattern for whatever key you happen to be playing in. The diatonic chords of the first, fourth, and fifth degrees will always be major and those of the second, third, and sixth degrees will always be minor. The diatonic chord of the seventh degree will always be diminished.


Don’t be overly concerned about the diatonic chord at the seventh degree being a diminished chord. Songs that use it are fairly rare. It would be better for you to know the major chord of the note of the dominant seventh, which is the note one full step lower than the root. In the key of C, for example, this would be B major. Many songs use what would be generically referred to as “VII,” as you’ll discover in Chapter 11.

Knowing the pattern of diatonic chords in relation to the key or key signature of a song is helpful for many reasons. Suppose you are accompanying a singer who has to sing a song in either D or E. Ignoring the diatonic chord of the seventh position (since it’s extremely unlikely to turn up), you’d most likely be choosing between playing the chords D, Em, Fm, G, A, and Bm in the key of D major or E, Fm, Gm, A, B, and Cm in the key of E.

Making the Guesswork Easier

Songs are made up of chords played in specific patterns (or progressions, if you prefer). While it is possible for any one chord to follow another, the truth is that some chords simply sound better when played in succession. Here are some simple guidelines to help you whenever you find yourself playing a song that uses primarily diatonic chords.

The “I” chord is the tonal center of the key. It is most often followed in songs by either the “IV” chord or the “V” chord. You will sometimes find the “vi” chord following the “I” chord, while the “ii” and “iii” chords only occasionally follow the “I” chord directly.

Using the key of C major as an example, this means that whenever you play a C chord, it’s most likely to be followed by either F or G, somewhat likely to be followed by Am and slightly less likely to be followed by Dm or Em.

The “ii” chord is most often followed by the “V” chord. In fact, going from “ii” to “V” to “I” is a very popular chord series that is used in songs of all musical genres.

In terms of frequency, the “I,” “IV,” and “vi,” chords follow the “ii” chord less often than the “V” chord does, while the “iii” chord only occasionally does.

Using the key of C major as an example, this means that whenever you play a Dm chord, it’s most likely to be followed by a G chord. You will sometimes follow a Dm with C, F, or Am and less often with Em.

The “iii” is most often followed by the “vi” chord. The “IV” chord is the second most likely follower. Following the “iii” chord with the “I,” “ii,” or “V” chord does happen but not as often as with the other two chords.

Using the key of C major as an example, this means that whenever you play an Em chord, it’s most likely to be followed by an Am chord. The next best guess would be to use an F chord with C, Dm, and G following the Em only occasionally.

The “IV” chord is most likely to be followed by either the “V” chord or the “I” chord. You will sometimes find the “ii” or “vi” following it, and occasionally the “iii.”

Using the key of C major as an example, this means that whenever you play an F chord, it’s most likely to be followed by a G or C chord. The next best guess would be to follow the F with either the Am or Dm and not worrying too much about it being followed by an Em.

Far and away, the “V” chord is most often followed by the “I” chord, although there will be times when the “IV” and “vi” chords seem to be used quite a bit, too. Of the other diatonic chords, the “V” is least followed by the “ii” and “iii” chords.

Using the key of C major as an example, this means that whenever you play a G chord, it’s most likely to be followed by a C chord. The next best choices would be either F or Am, with Dm and Em being less likely candidates.

The “ii” and “V” chords are most likely to follow the “vi” chord in a chord progression. The “IV” and “iii” chords are the next best choices, but only slightly better than going with the “I” chord.

Using the key of C major as an example, this means that whenever you play an Am chord, it’s most likely to be followed by either Dm or G. F, Em, and C do occasionally follow Am but not quite as often as Dm and G will.

You also want to notice clues from the musical context of the song you’re playing. For example, if you’ve played the “vi” chord followed by the “V” chord followed by the “IV” chord followed by the “iii” chord, “ii” (followed by “I”) seems to be a good bet because of the descending sequence of chords.

A Diatonic Chart for Every Key

The longer you play guitar, and music in general, the more you will see these patterns of diatonic chords in the songs you play. Right now you are looking through a veritable maze of charts, but it is surprising how quickly you will pick up on the ideas and terminology.

To help, here is a chart of the diatonic chords in positions one through six of each of the 12 possible key signatures. Again, the chord at the seventh position occurs so rarely that you don’t have to worry much about it.

Remember that in any song, the chords you are most likely to find are the “I,” “IV,” and “V” chords with the “ii,” “iii,” and “vi” chords being there, but not usually as prominent.

This chart can, and will, be incredibly handy. Almost all blues songs use only the “I,” “IV,” and “V” chords of any given key. So if someone told you they wanted to play a blues song in the key of D, you’d know that the song would probably just have D, G, and A chords in it. So make your own copy and keep it close!


This knowledge of diatonic chords allows you to transpose songs into different keys. To transpose is to change the notes and chords from one key to another.

Suppose you run across a song you like but the chords are difficult for you to play. For example, say the song in question is in the key of A and uses the chords A, Fm, D, and E.

Looking at the chart on the previous page, you see that in the row for the key of A (the key will be under the column marked “I”), these are the I, vi, IV, and V chords. Take a look at the other rows and see if there is a set of I, vi, IV, and V chords you would prefer to play. Chances are you’ll like the chords in the key of C (C, Am, F, and G), the key of D (D, Bm, G, and A), and the key of G (G, Em, C, and D).

When transposing, focus on the root note of the chord and don’t worry about how complicated a chord it might seem to be. You simply transfer all of the chord’s “baggage” to the new root note. Suppose the chords in our last example were A, Fm7, Dadd9, and Esus4. In the key of C, that chord progression would transpose to C, Am7, Fadd9, and Gsus4.

Remember, too, that while many songs use only diatonic chords, you will often run into songs that borrow chords from other keys. If the Fm7 in the key of A of the last example had been F7, that would have transposed to A7 in the key of C.

Putting Theory to Practice

The act of transposing is also a great way to get the pattern of diatonic scales ingrained into your guitar theory repertoire. Practice transposing very easy songs first, meaning songs that don’t have very many chord changes. Write down your first attempts at transposing, and feel free to keep the “diatonic chords for all 12 keys” chart right at hand. You’re bound to make some mistakes but you will soon find yourself capable of transposing three- and four-chord songs fairly easily and quickly.

Also be sure to transpose songs into keys that have chords you can play. It makes no sense to change a song with G and C chords to one with D and G chords. It’s actually very smart to be able to play any song in two or three different keys, as you’ll read about in Chapter 18.

As you get more comfortable with transposing and more confident in your knowledge of diatonic chords, try transposing songs in your head. Again, start with simple songs that you know well and that have four or fewer different chords. As you play them, you should find yourself thinking of the chords in both their “actual names” as well as their generic diatonic equivalents. When this breakthrough occurs, and it will, you should also find that your ability to memorize songs has magically improved. And that happened without you even being aware of working on it.

The Least You Need to Know

  • Diatonic chords are made up solely of the notes from a single, specific Major Scale.
  • The pattern for diatonic chords of any Major Scale is: major, minor, minor, major, major, minor, and diminished.
  • Knowing the diatonic chords of a key can help you make fairly good educated guesses as to what chord may be coming next in a song.
  • To transpose means to change all the notes and chords of a song from one key into another, maintaining all relative interval relationships.
  • Practice transposing songs as a way to solidify your knowledge of the diatonic chord pattern.