Understanding Chord Progressions
Start writing your own songs using diatonic chords.
This lesson is a sample from the Acoustic Rock Essentials course.
When you hear a song that sticks in your ear, it’s often the chord progression that catches your attention. Maybe it’s a classic and familiar-sounding set of chords that just sound right together, or maybe it’s an unexpected chord change you’ve never heard before. No matter how classic or quirky a chord progression may be, it can be interpreted and analyzed through a simple framework musicians refer to as chord functions. These functions show the relationship between chords in any given key, and they can help you learn chord progressions and play along with others by just calling out a few numbers—and even create ear-catching chord progressions of your own. In this lesson, we’ll take a look at chord functions and how to find them in any key and apply them to chord progressions found in many popular songs.
Diatonic Chord Progressions
Chords within a progression all relate to each other in some way, and those relationships are often constructed around a given scale—the scale with the same letter name as the key you’re in. For starters, this means that if you’re in the key of C major, you can build a series of chords that will work well together from the notes of the C-major scale (Example 1, 2:02). To do this, create triads (three-note chords) by stacking a pair of third intervals on top of each scale tone (Example 2, 2:27).
Don’t worry about playing the chords in Example 2 the way they’re written here. We’re more concerned with their letter names, and you can play the standard chord shapes you already know—like their root-position or barre-chord counterparts. Look above each chord symbol in Example 2, and you’ll see a Roman numeral. These are the diatonic chord functions (diatonic means that melody notes and harmony are created from the same seven notes of the accompanying scale). The upper- and lowercase Roman numerals help us distinguish major from minor—uppercase numerals indicate a major chord, while lowercase numerals indicate a minor chord. (The one exception is the diminished vii (viio) chord, which is rarely used.)
The most important chords in any key are the I and V chords, and in rock music, the IV chord is close behind. The V chord creates a sense of tension that pulls your ear back to the I chord, so you’ll often hear that chord played before a progression returns to the I, as in Example 3 (3:58) (where the V chord leads back to I on each repeat). You’ve probably heard this chord progression countless times; it’s similar to the one in the Beatles’ version of “Twist and Shout.” We call it a I–IV–V (“one–four–five”) progression, following the Roman numerals assigned to each chord. Another popular progression is I–vi–ii–V (“one–six–two–five”), which you’ll find in songs like the Beatles “That Boy” and “Yes It Is” (Example 4, 4:40).
Even though the V chord pulls most strongly back to I, it doesn’t always precede the I chord. You’ll hear many other chords resolving to I as well, like the IV–I progression in Example 5 (5:20) (often called the “amen” progression, because it’s used in many hymns).
Different Keys, Same Relationships
The benefit to thinking about a chord’s function is that the relationships stay the same, no matter what key you’re in. That means that you can easily transpose chord progressions from one key to another, or quickly call out a chord progression to a group of musicians, by simply calling out the numbers and key (“It’s a I–iii–vi–ii–V in the key of C”). When you first start thinking about progressions in this way, you’ll need to build your set of chords in the keys you use from the key’s corresponding scale, but once you’ve done it enough, you’ll soon know which chords to use in any key—especially the keys guitarists use most often, like E, A, D, G, and C.
Let’s try this out in the key of A. We’ll start with the A major scale (Example 6, 6:18) and add a pair of triads above each scale degree to get the diatonic chords in A (Example 7, 6:36). Now you can play everything you just played in the key of C by following the numbers. The “Twist and Shout”-type I–IV–V progression becomes an A–D–E progression (Example 8, 7:15), and the I–vi–ii–V is now A–F#m–Bm–E (Example 9, 7:36). Compare Examples 8 and 9 to Examples 3 and 4 to see the similarities between these chord progressions, even though they’re in different keys.
Chord Progressions in Minor Keys
You can create minor-key chord progressions in the same way we did for major keys: by first finding the chord functions so you know which chords work together in any key, then fashioning progressions out of the appropriate chords. Example 10 (8:45) starts with an A-minor scale, and Example 11 (9:02) builds chord functions by stacking thirds on each scale degree. The major and minor chords occur in different places than they do in major keys; for minor keys, the i, iv, and v chords are minor, while the bIII, bVI, and bVII chords are major. The diminished chord falls in the ii spot, but musicians usually substitute something for that diminished chord, so we’ll use one of the most popular: a regular minor chord built on the second note of the scale (Example 12, 9:49).
Let’s try these out with a popular minor-key chord progression—the i–bVII–bVI shown in Example 13 (10:05) (in the key of Am). Similar progressions can be heard in classic rock songs like “All Along the Watchtower” and the climactic ending of “Stairway to Heaven.” Example 14 (10:39) shows another minor-key progression, this one similar to the Beatles hit “And I Love Her.” Notice how this one shows the interconnection between relative minor and major keys by sounding minor in the first few measures (key of Bm), but leaning toward the relative major (key of D) at the end of the phrase. This interplay between relative major and minor keys is a nifty trick.
Chord Functions with Barre Chords
Many people associate higher positions on the guitar neck with more complex playing, but when it comes to transposing chord progressions, open-position chords can actually be a bit confusing—you really have to think about the relationship between each chord and the next. Barre chords can make it easier to transpose your chord progressions to different keys. Because most guitarists use just two barre-chord shapes—the E shape (a six-string chord) and the A shape (a five-string chord), when you want to go to a different key, all you have to do is move those shapes around the neck.
To see how this works, let’s start with a I–IV–V chord progression in the key of C, but this time let’s use barre chords up the neck, as in Example 15 (12:31). To play the same progression in the key of A, all you need to do is start three frets lower (at the fifth fret), and the shapes remain the same (Example 16, 12:52). Want to play I–IV–V in the key of F? Just slide your index finger down to the first fret, where the F note is, and play the same pattern (Example 17, 13:15). Want to move the whole thing to the key of Bb? Slide up to the sixth fret (Example 18, 13:35), and you’re good to go! Navigating through chord changes is much easier this way, because you’ll quickly learn where each chord is relative to the I chord.
In Examples 15–18, we stuck to two barre-chord shapes with the I chord rooted on the sixth string. But sometimes your hand may be far away from that I chord when you need to start a chord progression. Instead of leaping across the fingerboard to hit the I chord rooted on the sixth string, you can play a I chord with its root on the fifth string. The mechanics of the fingerboard are such that if the I chord on the sixth string is far away, another I chord with a root on the fifth string will usually be nearby! Example 19 (14:31) shows a I–IV–V chord progression using a I chord rooted on the fifth string in the key of Eb, and Example 20 (14:50) shows it two frets higher in the key of F.
Choosing between I chords rooted on the fifth or sixth strings also allows you to play the progression on the easiest part of the fingerboard in any given key. Go back to Example 17 to play the I–IV–V chord down near the nut of your guitar. Then notice how much easier it is to play the same chords in Example 20, because barre-chord shapes are easier to play up the neck.
You can do the same thing with minor keys, as well. Let’s try a i–bVII–bVI progression in the key of C minor (Example 21, 15:40). To play it in the key of B minor, simply slide down a fret so that the root of the i chord is on the seventh-fret B note (Example 22, 16:07). You can also play the i–bVII–bVI progression by using i chords rooted on the fifth string, as in Example 23 (16:34) (key of E minor) or Example 24 (16:58) (key of G minor).
Now let’s try a complete song! I play “Is There Something I Can Say” with a capo on the sixth fret, using chord changes similar to what the Beatles and other pop icons have used in many of their tunes. The song starts rocking between the I and vi chords (measures 1–3), then goes to the IV chord in measure 4, followed by one of the most common mini progressions in pop, rock, and jazz in measures 5–7, the ii–V–I. The chorus adds a iii chord (Em), and measures 25–29 are a short tag that lengthens the song by a few measures—a nifty Beatles-esque tool to make the last chorus more memorable.
Now that you know a handful of chords that are certain to fit together in any given key, you’re well on your way to becoming a hit songwriter—the best way to move forward is to experiment with different combinations of diatonic chords to construct progressions of your own.
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