How to Use the Circle


(entry for 1/10/2025)


Last post we talked about the Circle of 5ths and how to construct one. This time we’re going to talk about how to use it and why it’s important to the study of harmony.

We’ve already mentioned that keys arranged a fifth apart have either one more sharp or one more flat than the key before, depending on which way we go around the circle. (Remembering that adding a sharp is the same as subtracting a flat, and vice versa.) The next thing to notice is that keys which are only one signature element away from each other are more closely related than other pairs of keys. For example: The key of D major (two sharps) is more closely related to G major (one sharp) than it is to E major (four sharps). Another example: The key of D-flat Major (five flats) is more closely related to A-flat Major (four flats) than it is to B-flat major (two flats). Etc. In fact, you can go temporarily to a chord from a key that is only one sharp or one flat away from the key you started from without leaving the key you are in at all!

To show how this is so, we need to introduce a new concept: the wedge. An illustration of the wedge is at the head of this post, and the first thing you’ll notice about it is that it uses numbers instead of letters.

The really cool thing about the wedge is that you can move it anywhere on the circle (rotating it as you go, so it matches the shape of the circle) and the relationships of the numbers remains the same.

For example, in the key of C major (no sharps, no flats), the chord on the outside of the circle to the right of the C is G. We already know that G is a fifth above C, and that’s why there’s a Roman Numeral five (V) in that position on the wedge. Likewise, if you go left on the circle (counterclockwise), the next major key in that position is F, which is a fifth lower than C. But it’s also a fourth higher than C, which is why it has the Roman Numeral four (IV) on the wedge. And the three relative minors of the major keys on the outside of the circle are determined in the same manner, by seeing at what note of the major scale the name of the minor chord is located. From left to right on the inner part of the wedge, the note ‘d,’ the note ‘a,’ and the note ‘e,’ are based on the second, the sixth, and the third note of the C major scale, which is why the Roman Numerals for those minor keys are two (ii), six (vi), and three (iii). And, just as we write the minor key names using lower case letters, we write the numbers on the wedge for the minor keys using lower case Roman Numerals.

OK, there’s really no such things as lower case Roman Numerals (!), but we have invented them to show the kinds of chords that are represented in the wedge. (Music is not math!)

Now let’s rotate the wedge two notches on the circle to the right (clockwise). The one chord (I) is now D. The five chord (V) is now A. You can go ahead and apply the same principle throughout the wedge, and in every case you will get the correct answer going either from key name to number or the other way around.

At this point I should explain something: Roman Numerals are used to represent the Key relationships only in Classical Music. In popular music, we use something called Nashville Numbers (because they grew out of the Country Music traditions that have their ‘headquarters’ in that city). Nashville numbers are simply plain old ordinary Arabic numerals, the ones we use when we learn arithmetic: 1, 2, 3, etc. So when we’re doing analysis of popular music, or Country and Western, or jazz, or blues, or any other kind of non-Classical music, we use, from left to right, on the outside of the wedge, 4, 1, and 5, and on the inside of the circle 2, 6, and 3. They mean exactly the same thing, except that you can no longer tell which keys are Major and which are Minor, which turns out to be a problem later on, which is why I prefer the Classical way. (Also, that’s the way I learned it, starting at age 5. I never heard of Nashville Numbers until many years later.) There’s no such thing as a lower case Arabic numeral!

In some musical performance groups in Nashville and related locations, when some of the musicians don’t read music notation, and when they’re learning a new piece for the first time, the leader may shout out the chord changes using letter names, or they may shout out the changes using numbers. So, for example, if the piece is in D and the leader shouts out ‘Five,’ the members know that the 5 chord in D is the chord ‘A major,’ and that’s the chord they play at that moment. Etc. Either way works fine, and some leaders prefer one approach and some the other. Neither one is right or wrong, it’s just a matter of preference.

By now you may have noticed that there’s a number missing in the wedge, regardless of which type of numeral we are using: we’re missing the seven (7 or VII). Why?

Remember what we learned about the limitation of Western Music regarding the Series of Partials? Which partial is not part of our scales? Right, the 7th partial. That’s why the Seven is missing in the wedge. (People performing Middle Eastern Music don’t use the concept of the wedge, and they don’t use the concept of the Circle of 5ths. Those ideas work only if you are using the Tempered Scale, which they are not using.)

But we haven’t covered yet the very most important aspect of the wedge (or of the Circle, for that matter). Namely, if you’re in a Major Key, you can use any of the chords in the wedge without leaving the key!

Example: if you’re in the key of F Major, the chords B-flat major and C major (the IV and V chords) are still considered part of the key of F major, and the ‘d minor,’ ‘a minor,’ and ‘e minor’ chords are also still part of that same key of F major. Thus, there is a lot of variety available in any given key. Sometimes, the composer or arranger has limited themselves to two or three chords (so-called two-chord and three-chord songs), and sometimes they let themselves get even more creative. They might have a four-chord song in which the 6 chord (vi) is used some. As long as they don’t exceed the six chords in the wedge, they haven’t broken any ‘rules.’

Take ‘Red River Valley,’ for example. If we’re playing it in F major, it begins on that chord. “From this valley they say you are . . .”-- all of those melody notes are accompanied by the F major triad, so far. But when we get to the word “going,” we have a new chord. Namely, the B-flat major chord. Why? Because the melody note on the syllable “go-” is a D, and there is no D in the F Major chord. So to accommodate the D, we use the B-flat major chord, which does have a D in it! Likewise, when we get to the word “miss,” we go back to the F major chord again, and when we get to the “smile,” we go to the C chord, because the melody hits a G at that point, and there is no G in the F Major chord, but there is a G in the C chord.

In this same manner you can work on through the rest of the song, and you’ll discover that you need only a total of three different chords to fit the melody-- F major, B-flat major, and C major. (The 1, 4, and 5 chords in the wedge.) No minors needed! It’s a three-chord song, which is by far the most popular type of song in Folk and Old-fashioned Country types of music. (Though many of the more modern Country Songs use four or even five chords, though seldom all six.)

Think through all the really old songs you know. Odds are that they’re mostly three-chord and two-chord songs (the latter of which use only the 1 and 5 chords). A few may be four-chord songs, some of which use a chord that is not in the wedge (!), which brings up a whole new topic: Leaving the wedge. We’ll cover that idea in the next post.

But an important point before we go there: the wedge as shown above applies ONLY to major keys. If we're in a minor key we have to renumber everything. Stay tuned!


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copyright ©2025, LegendKeeper LLC


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